Add ExecuteJavaScriptForTest and make all tests use it

Additionally, restrict the URLs that ExecuteJavaScript can be invoked on
to chrome-controlled URLs.

R=jam@chromium.org
BUG=507809

Review URL: https://codereview.chromium.org/1123783002

Cr-Commit-Position: refs/heads/master@{#340231}
61 files changed