DevTools: Add autocomplete values for CSS contain

BUG=619844

Review-Url: https://codereview.chromium.org/2085523003
Cr-Commit-Position: refs/heads/master@{#402270}
diff --git a/third_party/WebKit/Source/devtools/front_end/sdk/CSSMetadata.js b/third_party/WebKit/Source/devtools/front_end/sdk/CSSMetadata.js
index 421c6522..2f53137 100644
--- a/third_party/WebKit/Source/devtools/front_end/sdk/CSSMetadata.js
+++ b/third_party/WebKit/Source/devtools/front_end/sdk/CSSMetadata.js
@@ -639,6 +639,9 @@
         "normal", "multiply", "screen", "overlay", "darken", "lighten", "color-dodge", "color-burn", "hard-light", "soft-light",
         "difference", "exclusion", "hue", "saturation", "color", "luminosity", "unset"
     ] },
+    "contain": { values: [
+        "none", "strict", "content", "size", "layout", "style", "paint"
+    ] }
 }
 
 /**