Revert 271398 "Blink roll 174243:174291"

This was the only CL in this build:

Test failures: http://build.chromium.org/p/chromium.mac/builders/Mac%2010.7%20Tests%20%28dbg%29%281%29/builds/23684

browser_tests browser_tests browser_tests 381 disabled 5 flaky failed 5 ( 24 mins, 12 secs )
stdio
PRE_ThemeDataPackInvalid
ThemeDataPackInvalid
ContextMenusAPI_Basic
Shim_TestNewWindow
SpeechRecognitionAPI_HasPermissionDeny

> Blink roll 174243:174291
> 
> http://build.chromium.org/f/chromium/perf/dashboard/ui/changelog_blink.html?url=/trunk&range=174243:174291&mode=html
> TBR=
> BUG=
> 
> Review URL: https://codereview.chromium.org/291923002

TBR=eseidel@chromium.org

Review URL: https://codereview.chromium.org/295703002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@271418 0039d316-1c4b-4281-b951-d872f2087c98

DEPS

@@ -28,7 +28,7 @@ vars = {
   "libcxxabi_revision": "206024",
   "webkit_trunk": "http://src.chromium.org/blink/trunk",
   "nacl_trunk": "http://src.chromium.org/native_client/trunk",
-  "webkit_revision": "174291",
+  "webkit_revision": "174243",
   "chromium_git": "https://chromium.googlesource.com",
   "chromiumos_git": "https://chromium.googlesource.com/chromiumos",
   "skia_git": "https://skia.googlesource.com",