DevTools: unflake the page enable-disable test.

BUG=280921
TBR=vsevik

Review URL: https://codereview.chromium.org/23537004

git-svn-id: svn://svn.chromium.org/blink/trunk@156920 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Test XMLHttpRequest with responseType set to 'json' for invalid UTF-8 input

BUG=119256

Review URL: https://chromiumcodereview.appspot.com/23295018

git-svn-id: svn://svn.chromium.org/blink/trunk@156922 bbb929c8-8fbe-4397-9dbb-9b2b20218538