Revert 222370 "Put the Vector size back to 16 whilst I investiga..."

> Put the Vector size back to 16 whilst I investigate perf regressions.
> 
> BUG=286696,286604,285442
> R=isherman@chromium.org
> 
> Review URL: https://codereview.chromium.org/23435004

TBR=cevans@chromium.org

Review URL: https://codereview.chromium.org/23654046

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@223571 0039d316-1c4b-4281-b951-d872f2087c98

build/common.gypi

@@ -1922,7 +1922,7 @@
       # Set this to use the new DX11 version of ANGLE.
       # TODO(apatrick): Remove this when the transition is complete.
       'ANGLE_DX11',
-      'WTF_VECTOR_INITIAL_SIZE=16',
+      'WTF_VECTOR_INITIAL_SIZE=4',
     ],
     'conditions': [
       ['(OS=="mac" or OS=="ios") and asan==1', {