Commit engine.realm as empty (#160541)

- only set it when the environment FLUTTER_REALM is present
diff --git a/.gitignore b/.gitignore
index 4424715..2785121 100644
--- a/.gitignore
+++ b/.gitignore
@@ -3,7 +3,6 @@
 
 # This is dynamic in a monorepo
 bin/internal/engine.version
-bin/internal/engine.realm
 
 # Miscellaneous
 *.class
diff --git a/bin/internal/engine.realm b/bin/internal/engine.realm
new file mode 100644
index 0000000..e69de29
--- /dev/null
+++ b/bin/internal/engine.realm
diff --git a/bin/internal/update_dart_sdk.ps1 b/bin/internal/update_dart_sdk.ps1
index 5f3c6ee..cc71521 100644
--- a/bin/internal/update_dart_sdk.ps1
+++ b/bin/internal/update_dart_sdk.ps1
@@ -41,25 +41,11 @@
         # The realm on CI is passed in.
         if ($Env:FLUTTER_REALM) {
             [System.IO.File]::WriteAllText("$flutterRoot\bin\internal\engine.realm", $Env:FLUTTER_REALM, $utf8NoBom)
-            $engineRealm = "$Env:FLUTTER_REALM"
-        }
-        else {
-            if (Test-Path -Path "$flutterRoot\bin\internal\engine.realm") {
-                $engineRealm = (Get-Content "$flutterRoot\bin\internal\engine.realm")
-            }
         }
     }
-    else {
-        # Release branch - these files will exist
-        $engineVersion = (Get-Content "$flutterRoot\bin\internal\engine.version")
-        $engineRealm = (Get-Content "$flutterRoot\bin\internal\engine.realm")
-    }
 }
-else {
-    # Non-fusion repository - these files will exist
-    $engineVersion = (Get-Content "$flutterRoot\bin\internal\engine.version")
-    $engineRealm = (Get-Content "$flutterRoot\bin\internal\engine.realm")
-}
+$engineVersion = (Get-Content "$flutterRoot\bin\internal\engine.version")
+$engineRealm = (Get-Content "$flutterRoot\bin\internal\engine.realm")
 
 $oldDartSdkPrefix = "dart-sdk.old"
 
diff --git a/bin/internal/update_dart_sdk.sh b/bin/internal/update_dart_sdk.sh
index f33de37..0c636eb 100755
--- a/bin/internal/update_dart_sdk.sh
+++ b/bin/internal/update_dart_sdk.sh
@@ -39,22 +39,11 @@
     # The realm on CI is passed in.
     if [ -n "${FLUTTER_REALM}" ]; then
       echo $FLUTTER_REALM > "$FLUTTER_ROOT/bin/internal/engine.realm"
-      ENGINE_REALM="$FLUTTER_REALM"
-    else
-      if [ -f "$FLUTTER_ROOT/bin/internal/engine.realm" ]; then
-        ENGINE_REALM=$(cat "$FLUTTER_ROOT/bin/internal/engine.realm" | tr -d '[:space:]')
-      fi
     fi
-  else
-    # Release branch - these files will exist
-    ENGINE_VERSION=$(cat "$FLUTTER_ROOT/bin/internal/engine.version")
-    ENGINE_REALM=$(cat "$FLUTTER_ROOT/bin/internal/engine.realm" | tr -d '[:space:]')
   fi
-else
-  # Non-fusion repository - these files will exist
-  ENGINE_VERSION=$(cat "$FLUTTER_ROOT/bin/internal/engine.version")
-  ENGINE_REALM=$(cat "$FLUTTER_ROOT/bin/internal/engine.realm" | tr -d '[:space:]')
 fi
+ENGINE_VERSION=$(cat "$FLUTTER_ROOT/bin/internal/engine.version")
+ENGINE_REALM=$(cat "$FLUTTER_ROOT/bin/internal/engine.realm" | tr -d '[:space:]')
 
 if [ ! -f "$ENGINE_STAMP" ] || [ "$ENGINE_VERSION" != `cat "$ENGINE_STAMP"` ]; then
   command -v curl > /dev/null 2>&1 || {