Enable slimming paint by default (for trybots only)

Source/web/tests/WebViewTest.cpp

Index: Source/web/tests/WebViewTest.cpp
diff --git a/Source/web/tests/WebViewTest.cpp b/Source/web/tests/WebViewTest.cpp
index 7aaa5495fe5a6014f9ea5d54af442e428c149908..4e6a6f98cb3b5c14536f99a55699bff9d9da0683 100644
--- a/Source/web/tests/WebViewTest.cpp
+++ b/Source/web/tests/WebViewTest.cpp
@@ -506,7 +506,7 @@ TEST_F(WebViewTest, SetBaseBackgroundColorBeforeMainFrame)
     frame->close();
 }
 
-TEST_F(WebViewTest, SetBaseBackgroundColorAndBlendWithExistingContent)
+TEST_F(WebViewTest, DISABLED_SetBaseBackgroundColorAndBlendWithExistingContent)

[wkorman, 2015/06/09 23:31:06]

Do you remember what prompted need to disable this? It hasn't come up yet in
failures. Maybe the underlying issue has since been resolved?

[Xianzhu, 2015/06/09 23:52:19]

Perhaps because of incompatible painting method at that time. We are using
SkPictureRecorder now so the incompatibility should be gone.

Just remembered that I disabled the tests because at that time I modified
RuntimeEnabledFeatures.in to enable slimming paint but later found it didn't
work (because the flag is overridden by chrome). I should remove all the
DISABLED_ prefixes.

 {
     const WebColor kAlphaRed = 0x80FF0000;
     const WebColor kAlphaGreen = 0x8000FF00;