[webkit-line-clamp] Enable BlockFlowHandlesWebkitLineClamp by default.

As above. This is attached to a feature flag of the same name.

There are a couple of additional failures due to this:
external/wpt/css/css-overflow/webkit-line-clamp-008.html
 - Fails due to applying line-clamping to children individually.
   (Incorrect test).
external/wpt/css/css-overflow/webkit-line-clamp-025.html
 - Fails on Mac due to slightly different word sizing. Need to make
   test more robust.
external/wpt/css/css-overflow/webkit-line-clamp-029.html
 - Fails due to applying line-clamping to children individually.
   (Incorrect test).

The other rebaselines fall into two categories.
1) Text shaping differences.
2) Fewer (but still correct) paint invalidations.

Bug: 993813
Change-Id: Idb0c546620150d381a3b21baf898bb6d11516f54
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2222621
Commit-Queue: Ian Kilpatrick <[email protected]>
Reviewed-by: Chris Harrelson <[email protected]>
Reviewed-by: Scott Violet <[email protected]>
Reviewed-by: Koji Ishii <[email protected]>
Cr-Commit-Position: refs/heads/master@{#774102}
diff --git a/third_party/blink/common/features.cc b/third_party/blink/common/features.cc
index 866565f4..f22908a6 100644
--- a/third_party/blink/common/features.cc
+++ b/third_party/blink/common/features.cc
@@ -470,7 +470,7 @@
     base::FEATURE_ENABLED_BY_DEFAULT};
 
 const base::Feature kBlockFlowHandlesWebkitLineClamp{
-    "BlockFlowHandlesWebkitLineClamp", base::FEATURE_DISABLED_BY_DEFAULT};
+    "BlockFlowHandlesWebkitLineClamp", base::FEATURE_ENABLED_BY_DEFAULT};
 
 const base::Feature kBlockHTMLParserOnStyleSheets{
     "BlockHTMLParserOnStyleSheets", base::FEATURE_DISABLED_BY_DEFAULT};