Upgrade TargetedStyleRecalc to status=stable.

The feature has been at status=experimental for over a month, and all known bugs have been fixed.

BUG=335247

Review URL: https://codereview.chromium.org/208153007

git-svn-id: svn://svn.chromium.org/blink/trunk@169765 bbb929c8-8fbe-4397-9dbb-9b2b20218538

third_party/WebKit/Source/platform/RuntimeEnabledFeatures.in

@@ -111,7 +111,7 @@ SVGPaintOrder status=stable
 
 // Enable optimizations to recalculate style on the fewest possible number of
 // elements when updating classes, ids or attributes of DOM elements.
-TargetedStyleRecalc status=experimental
+TargetedStyleRecalc status=stable
 
 // Many websites disable mouse support when touch APIs are available.  We'd
 // like to enable this always but can't until more websites fix this bug.