Roll src/third_party/WebKit ae50934:395f4d8 (svn 189273:189287)

Summary of changes available at:
https://chromium.googlesource.com/chromium/blink/+log/ae50934..395f4d8

TBR=junov@chromium.org,vsevik@chromium.org

Review URL: https://codereview.chromium.org/886143002

Cr-Commit-Position: refs/heads/master@{#314028}

DEPS

@@ -34,7 +34,7 @@ vars = {
   'llvm_url': 'http://src.chromium.org/llvm-project',
   'llvm_git': 'https://llvm.googlesource.com',
   'webkit_trunk': 'http://src.chromium.org/blink/trunk',
-  'webkit_revision': 'ae5093413a478b2815790cfe187c725e757559c8', # from svn revision 189273
+  'webkit_revision': '395f4d832255ec386b99e9181164727fea22ff13', # from svn revision 189287
   'chromium_git': 'https://chromium.googlesource.com',
   'chromiumos_git': 'https://chromium.googlesource.com/chromiumos',
   'pdfium_git': 'https://pdfium.googlesource.com',