Revert of Roll src/third_party/WebKit 698efc0:7d47c95 (svn 192500:192506)...

Revert of Roll src/third_party/WebKit 698efc0:7d47c95 (svn 192500:192506) (patchset #1 id:1 of https://codereview.chromium.org/1037703002/)

Reason for revert:
Broke compilation with GN:

https://build.chromium.org/p/chromium.mac/builders/Mac%20GN%20%28dbg%29/builds/6697/steps/gn/logs/stdio

caused by this Blink commit:
https://chromium.googlesource.com/chromium/blink/+/7d47c95bc49510d29e36fc2895eef3e67706ef41

Original issue's description:
> Roll src/third_party/WebKit 698efc0:7d47c95 (svn 192500:192506)
>
> Summary of changes available at:
> https://chromium.googlesource.com/chromium/blink/+log/698efc0..7d47c95
>
> TBR=jchaffraix@chromium.org
>
> Committed: https://crrev.com/60a49fc315e7eaed780da86aad1eecd40f149f70
> Cr-Commit-Position: refs/heads/master@{#322139}

TBR=jchaffraix@chromium.org,blink-deps-roller@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true

Review URL: https://codereview.chromium.org/1032603004

Cr-Commit-Position: refs/heads/master@{#322154}

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': '7d47c95bc49510d29e36fc2895eef3e67706ef41', # from svn revision 192506
+  'webkit_revision': '698efc02bc700d7165ddd7b4be9ed2d9469a90a6', # from svn revision 192500
   'chromium_git': 'https://chromium.googlesource.com',
   'chromiumos_git': 'https://chromium.googlesource.com/chromiumos',
   'pdfium_git': 'https://pdfium.googlesource.com',