Revert "Don't set document.title when there is no <head>"

This reverts https://src.chromium.org/viewvc/blink?revision=164582&view=revision

It caused Chromium browser_test ClickToPlayPluginTest.NoCallbackAtLoad to
fail, as that test expects to be able to set document.title to "OK"
read it back, in a document that apparently has no <head>.

TBR=wjmaclean@chromium.org
BUG=330165

Review URL: https://codereview.chromium.org/109823011

git-svn-id: svn://svn.chromium.org/blink/trunk@164623 bbb929c8-8fbe-4397-9dbb-9b2b20218538