Fix trailing truncated tags in view-source.

In addition, delete a few remnants of the old viewsource attribute.
view-source-no-refresh.php is a remnant of a previously deleted test, and
view-source-javascript-url-in-document.html tests behavior of the now-deleted
viewsource attribute.

Write new tests based on some of the other view-source test data still
lingering around. Finally, add a test for truncated tags case.

As part of these tests, modify HTMLViewSourceDocument slightly to produce a DOM
which round-trips correctly through an HTML parser. The old one was missing a
<head> and inserted child elements into <base>.

BUG=306286
TEST=fast/frames/viewsource/*

Review URL: https://codereview.chromium.org/26940002

git-svn-id: svn://svn.chromium.org/blink/trunk@159882 bbb929c8-8fbe-4397-9dbb-9b2b20218538