SImplify a few grid-as-flex-item related tests. (#23823)

Simplify a few grid-as-flex-item related test and added two additional tests.
diff --git a/css/css-grid/layout-algorithm/grid-as-flex-item-should-not-shrink-to-fit-001.html b/css/css-grid/layout-algorithm/grid-as-flex-item-should-not-shrink-to-fit-001.html
index 439cb2d..e0665d5 100644
--- a/css/css-grid/layout-algorithm/grid-as-flex-item-should-not-shrink-to-fit-001.html
+++ b/css/css-grid/layout-algorithm/grid-as-flex-item-should-not-shrink-to-fit-001.html
@@ -11,7 +11,6 @@
 <link rel="help" href="https://drafts.csswg.org/css-align-3/#align-grid">
 <link rel="match" href="../../reference/ref-filled-green-100px-square.xht">
 <meta name="assert" content="A single-line column flexbox shouldn't shrink-to-fit since its flex item is stretching in the main-axis, honoring the 'align-self: normal (behaves as 'stretch')'. The grid item's inline-size should be stretched as well, honoring its justify-self: 'normal' (behaves as 'stretch')">
-<link rel="stylesheet" href="/fonts/ahem.css">
 <style>
     body { overflow: hidden; }
     .flexbox {
@@ -20,13 +19,11 @@
         align-content: flex-start;
         width: 100px;
         height: 100px;
-        font: 25px/1 Ahem;
-        color: green;
+        background: red;
     }
     .grid {
         display: grid;
         align-items: baseline;
-        background: red;
     }
     .gridItem {
         background: green;
@@ -36,6 +33,6 @@
 <p>Test passes if there is a filled green square and <strong>no red</strong>.</p>
 <div class="flexbox">
     <div class="grid">
-        <div class="gridItem">XX</div>
+        <div class="gridItem"></div>
     </div>
 </div>
diff --git a/css/css-grid/layout-algorithm/grid-as-flex-item-should-not-shrink-to-fit-002.html b/css/css-grid/layout-algorithm/grid-as-flex-item-should-not-shrink-to-fit-002.html
index a8ddc06..4ddafec 100644
--- a/css/css-grid/layout-algorithm/grid-as-flex-item-should-not-shrink-to-fit-002.html
+++ b/css/css-grid/layout-algorithm/grid-as-flex-item-should-not-shrink-to-fit-002.html
@@ -10,8 +10,7 @@
 <link rel="help" href="https://drafts.csswg.org/css-align-3/#align-flex">
 <link rel="help" href="https://drafts.csswg.org/css-align-3/#align-grid">
 <link rel="match" href="../../reference/ref-filled-green-100px-square.xht">
-<meta name="assert" content="The align-content: 'stretch' prevents the multi-line column flexbox to shrink-to-fit (default behavior), hence the grid container will be stretched, honoring its align-self: 'normal (behaves as 'stretch'), so that its grid item, honoring its justify-self: 'normal' (behaves as 'stretch') ">
-<link rel="stylesheet" href="/fonts/ahem.css">
+<meta name="assert" content="The align-content: 'stretch' prevents the multi-line column flexbox to shrink-to-fit (default behavior), hence the grid container will be stretched, honoring its align-self: 'normal (behaves as 'stretch'), as well as its grid item, honoring its justify-self: 'normal' (behaves as 'stretch') ">
 <style>
     body { overflow: hidden; }
     .flexbox {
@@ -20,13 +19,11 @@
         align-content: stretch;
         width: 100px;
         height: 100px;
-        font: 25px/1 Ahem;
-        color: green;
+        background: red;
     }
     .grid {
         display: grid;
         align-items: baseline;
-        background: red;
     }
     .gridItem {
         background: green;
@@ -36,6 +33,6 @@
 <p>Test passes if there is a filled green square and <strong>no red</strong>.</p>
 <div class="flexbox">
     <div class="grid">
-        <div class="gridItem">XX</div>
+        <div class="gridItem"></div>
     </div>
 </div>
diff --git a/css/css-grid/layout-algorithm/grid-as-flex-item-should-not-shrink-to-fit-003.html b/css/css-grid/layout-algorithm/grid-as-flex-item-should-not-shrink-to-fit-003.html
index 2a3da50..73d2044 100644
--- a/css/css-grid/layout-algorithm/grid-as-flex-item-should-not-shrink-to-fit-003.html
+++ b/css/css-grid/layout-algorithm/grid-as-flex-item-should-not-shrink-to-fit-003.html
@@ -10,8 +10,7 @@
 <link rel="help" href="https://drafts.csswg.org/css-align-3/#align-flex">
 <link rel="help" href="https://drafts.csswg.org/css-align-3/#align-grid">
 <link rel="match" href="../../reference/ref-filled-green-100px-square.xht">
-<meta name="assert" content="A single-line column flexbox shouldn't shrink-to-fit since its flex item is stretching in the main-axis, honoring the 'align-self: normal (behaves as 'stretch')'. The grid item's inline-size should be stretched as well, honoring its justify-self: 'normal' (behaves as 'stretch')">
-<link rel="stylesheet" href="/fonts/ahem.css">
+<meta name="assert" content="A single-line column flexbox shouldn't shrink-to-fit since its flex item is stretching in the main-axis, honoring the 'align-self: normal (behaves as 'stretch')'. The vertical grid item's inline-size should be stretched as well, honoring its justify-self: 'normal' (behaves as 'stretch')">
 <style>
     body { overflow: hidden; }
     .flexbox {
@@ -20,13 +19,11 @@
         align-content: flex-start;
         width: 100px;
         height: 100px;
-        font: 25px/1 Ahem;
-        color: green;
+        background: red;
     }
     .grid {
         display: grid;
         align-items: baseline;
-        background: red;
     }
     .gridItem {
         background: green;
@@ -37,6 +34,6 @@
 <p>Test passes if there is a filled green square and <strong>no red</strong>.</p>
 <div class="flexbox">
     <div class="grid">
-        <div class="gridItem">XX</div>
+        <div class="gridItem"></div>
     </div>
 </div>
diff --git a/css/css-grid/layout-algorithm/grid-as-flex-item-should-not-shrink-to-fit-004.html b/css/css-grid/layout-algorithm/grid-as-flex-item-should-not-shrink-to-fit-004.html
index 70fc92c..c3f9d9c 100644
--- a/css/css-grid/layout-algorithm/grid-as-flex-item-should-not-shrink-to-fit-004.html
+++ b/css/css-grid/layout-algorithm/grid-as-flex-item-should-not-shrink-to-fit-004.html
@@ -10,8 +10,7 @@
 <link rel="help" href="https://drafts.csswg.org/css-align-3/#align-flex">
 <link rel="help" href="https://drafts.csswg.org/css-align-3/#align-grid">
 <link rel="match" href="../../reference/ref-filled-green-100px-square.xht">
-<meta name="assert" content="The align-content: 'stretch' prevents the multi-line column flexbox to shrink-to-fit (default behavior), hence the grid container will be stretched, honoring its align-self: 'normal (behaves as 'stretch'), so that its grid item, honoring its justify-self: 'normal' (behaves as 'stretch') ">
-<link rel="stylesheet" href="/fonts/ahem.css">
+<meta name="assert" content="The align-content: 'stretch' prevents the multi-line column flexbox to shrink-to-fit (default behavior), hence the grid container will be stretched, honoring its align-self: 'normal (behaves as 'stretch'), as well as its vertical grid item, honoring its justify-self: 'normal' (behaves as 'stretch') ">
 <style>
     body { overflow: hidden; }
     .flexbox {
@@ -20,12 +19,10 @@
         align-content: stretch;
         width: 100px;
         height: 100px;
-        font: 25px/1 Ahem;
-        color: green;
+        background: red;
     }
     .grid {
         display: grid;
-        background: red;
     }
     .gridItem {
         background: green;
@@ -36,6 +33,6 @@
 <p>Test passes if there is a filled green square and <strong>no red</strong>.</p>
 <div class="flexbox">
     <div class="grid">
-        <div class="gridItem">XX</div>
+        <div class="gridItem"></div>
     </div>
 </div>
diff --git a/css/css-grid/layout-algorithm/grid-as-flex-item-should-not-shrink-to-fit-005.html b/css/css-grid/layout-algorithm/grid-as-flex-item-should-not-shrink-to-fit-005.html
index 4ca1525..4443314 100644
--- a/css/css-grid/layout-algorithm/grid-as-flex-item-should-not-shrink-to-fit-005.html
+++ b/css/css-grid/layout-algorithm/grid-as-flex-item-should-not-shrink-to-fit-005.html
@@ -11,7 +11,6 @@
 <link rel="help" href="https://drafts.csswg.org/css-align-3/#align-grid">
 <link rel="match" href="../../reference/ref-filled-green-100px-square.xht">
 <meta name="assert" content="A single-line column flexbox shouldn't shrink-to-fit since its flex item is stretching in the main-axis, honoring the 'align-self: normal (behaves as 'stretch')'. The grid item's inline-size should be stretched as well, honoring its justify-self: 'normal' (behaves as 'stretch')">
-<link rel="stylesheet" href="/fonts/ahem.css">
 <style>
     body { overflow: hidden; }
     .flexbox {
@@ -20,13 +19,11 @@
         align-content: flex-start;
         width: 100px;
         height: 100px;
-        font: 25px/1 Ahem;
-        color: green;
+        background: red;
     }
     .grid {
         display: grid;
         align-items: start;
-        background: red;
     }
     .gridItem {
         background: green;
@@ -36,6 +33,6 @@
 <p>Test passes if there is a filled green square and <strong>no red</strong>.</p>
 <div class="flexbox">
     <div class="grid">
-        <div class="gridItem">XX</div>
+        <div class="gridItem"></div>
     </div>
 </div>
diff --git a/css/css-grid/layout-algorithm/grid-as-flex-item-should-not-shrink-to-fit-006.html b/css/css-grid/layout-algorithm/grid-as-flex-item-should-not-shrink-to-fit-006.html
index 43051f9..7be46cd 100644
--- a/css/css-grid/layout-algorithm/grid-as-flex-item-should-not-shrink-to-fit-006.html
+++ b/css/css-grid/layout-algorithm/grid-as-flex-item-should-not-shrink-to-fit-006.html
@@ -10,8 +10,7 @@
 <link rel="help" href="https://drafts.csswg.org/css-align-3/#align-flex">
 <link rel="help" href="https://drafts.csswg.org/css-align-3/#align-grid">
 <link rel="match" href="../../reference/ref-filled-green-100px-square.xht">
-<meta name="assert" content="The align-content: 'stretch' prevents the multi-line column flexbox to shrink-to-fit (default behavior), hence the grid container will be stretched, honoring its align-self: 'normal (behaves as 'stretch'), so that its grid item, honoring its justify-self: 'normal' (behaves as 'stretch') ">
-<link rel="stylesheet" href="/fonts/ahem.css">
+<meta name="assert" content="The align-content: 'stretch' prevents the multi-line column flexbox to shrink-to-fit (default behavior), hence the grid container will be stretched, honoring its align-self: 'normal (behaves as 'stretch'), as well as grid item, honoring its justify-self: 'normal' (behaves as 'stretch') ">
 <style>
     body { overflow: hidden; }
     .flexbox {
@@ -20,13 +19,11 @@
         justify-content: stretch;
         width: 100px;
         height: 100px;
-        font: 25px/1 Ahem;
-        color: green;
+        background: red;
     }
     .grid {
         display: grid;
         align-items: start;
-        background: red;
     }
     .gridItem {
         background: green;
@@ -36,6 +33,6 @@
 <p>Test passes if there is a filled green square and <strong>no red</strong>.</p>
 <div class="flexbox">
     <div class="grid">
-        <div class="gridItem">XX</div>
+        <div class="gridItem"></div>
     </div>
 </div>
diff --git a/css/css-grid/layout-algorithm/grid-as-flex-item-should-not-shrink-to-fit-007.html b/css/css-grid/layout-algorithm/grid-as-flex-item-should-not-shrink-to-fit-007.html
new file mode 100644
index 0000000..ab0e591
--- /dev/null
+++ b/css/css-grid/layout-algorithm/grid-as-flex-item-should-not-shrink-to-fit-007.html
@@ -0,0 +1,39 @@
+<!DOCTYPE html>
+<meta charset="utf-8">
+<title>CSS Grid Layout Test: Evaluate the behavior of a grid container as Flexbox item</title>
+<link rel="author" title="Javier Fernandez Garcia-Boente" href="mailto:jfernandez@igalia.com">
+<link rel="help" href="https://drafts.csswg.org/css-grid/#layout-algorithm">
+<link rel="help" href="https://drafts.csswg.org/css-flexbox-1/#flex-lines">
+<link rel="help" href="https://drafts.csswg.org/css-flexbox-1/#propdef-flex-wrap">
+<link rel="help" href="https://drafts.csswg.org/css-flexbox-1/#propdef-align-content">
+<link rel="help" href="https://drafts.csswg.org/css-flexbox-1/#propdef-align-self">
+<link rel="help" href="https://drafts.csswg.org/css-align-3/#align-flex">
+<link rel="help" href="https://drafts.csswg.org/css-align-3/#align-grid">
+<link rel="match" href="../../reference/ref-filled-green-100px-square.xht">
+<meta name="assert" content="A single-line column flexbox shouldn't shrink-to-fit since its flex item is stretching in the main-axis, honoring the 'align-self: normal (behaves as 'stretch')'. The grid item's relative block size will be resolved againts the grid's row size, while its inline-size should be stretched as well, honoring its justify-self: 'normal' (behaves as 'stretch')">
+<style>
+    body { overflow: hidden; }
+    .flexbox {
+        display: flex;
+        flex-flow: column nowrap;
+        align-content: flex-start;
+        width: 100px;
+        height: 100px;
+        background: red;
+    }
+    .grid {
+        display: grid;
+        align-items: baseline;
+        grid-template-rows: 100px;
+    }
+    .gridItem {
+        background: green;
+        height: 100%;
+    }
+</style>
+<p>Test passes if there is a filled green square and <strong>no red</strong>.</p>
+<div class="flexbox">
+    <div class="grid">
+        <div class="gridItem"></div>
+    </div>
+</div>
diff --git a/css/css-grid/layout-algorithm/grid-as-flex-item-should-not-shrink-to-fit-008.html b/css/css-grid/layout-algorithm/grid-as-flex-item-should-not-shrink-to-fit-008.html
new file mode 100644
index 0000000..183a607
--- /dev/null
+++ b/css/css-grid/layout-algorithm/grid-as-flex-item-should-not-shrink-to-fit-008.html
@@ -0,0 +1,39 @@
+<!DOCTYPE html>
+<meta charset="utf-8">
+<title>CSS Grid Layout Test: Evaluate the behavior of a grid container as Flexbox item</title>
+<link rel="author" title="Javier Fernandez Garcia-Boente" href="mailto:jfernandez@igalia.com">
+<link rel="help" href="https://drafts.csswg.org/css-grid/#layout-algorithm">
+<link rel="help" href="https://drafts.csswg.org/css-flexbox-1/#flex-lines">
+<link rel="help" href="https://drafts.csswg.org/css-flexbox-1/#propdef-flex-wrap">
+<link rel="help" href="https://drafts.csswg.org/css-flexbox-1/#propdef-align-content">
+<link rel="help" href="https://drafts.csswg.org/css-flexbox-1/#propdef-align-self">
+<link rel="help" href="https://drafts.csswg.org/css-align-3/#align-flex">
+<link rel="help" href="https://drafts.csswg.org/css-align-3/#align-grid">
+<link rel="match" href="../../reference/ref-filled-green-100px-square.xht">
+<meta name="assert" content="A single-line column flexbox shouldn't shrink-to-fit since its flex item is stretching in the main-axis, honoring the 'align-self: normal (behaves as 'stretch')'. The grid item has a relative inline-size, which should be resolved against the stretched grid's inline-size.">
+<style>
+    body { overflow: hidden; }
+    .flexbox {
+        display: flex;
+        flex-flow: column nowrap;
+        width: 100px;
+        height: 100px;
+        background: red;
+    }
+    .grid {
+        display: grid;
+        justify-self: start;
+        align-items: baseline;
+    }
+    .gridItem {
+        background: green;
+        width: 100%;
+        height: 100px;
+    }
+</style>
+<p>Test passes if there is a filled green square and <strong>no red</strong>.</p>
+<div class="flexbox">
+    <div class="grid">
+        <div class="gridItem"></div>
+    </div>
+</div>