Fix flaky layout tests that rely on setTimeout()s firing after <body> is parsed
https://bugs.webkit.org/show_bug.cgi?id=112306

Reviewed by Eric Seidel.

These tests all rely in one way or another on the body of a setTimeout set in an inline <script> in the <head>
firing after the <body> element is generated by the HTML parser. This is a flaky pattern since the HTML parser
may yield when parsing a </script> or when runnnig out of bytes from the network. In practice, this pattern used
to be not terribly flaky for layout tests loaded from disk unless there was a large GC pause. However, since the
threaded HTML parser yields more frequently when hitting a </script> this flakes more.

These tests were found by identifying layout tests that call setTimeout before the document's body exists by
modifying the code, then intersecting that set with tests that are flaky on the chromium flakiness dashboard.

* editing/inserting/insert-text-into-empty-frameset-crash.html:
* editing/style/apply-style-crash.html:
* fast/block/float/float-originating-line-deleted-crash.html:
* fast/block/float/floats-not-cleared-crash.html:
* fast/block/line-layout/inline-box-wrapper-crash.html:
* fast/css/positioned-in-relative-position-inline-crash.html:
* fast/css/user-stylesheet-crash.html:
* fast/encoding/script-in-head.html:
* fast/forms/textarea-placeholder-relayout-assertion.html:
* fast/frames/seamless/seamless-form-get.html:
* fast/frames/seamless/seamless-form-post-named.html:
* fast/frames/seamless/seamless-window-location-href.html:
* fast/frames/seamless/seamless-window-location-replace.html:
* fast/inline/update-always-create-line-boxes-full-layout-crash.html:
* fast/innerHTML/innerHTML-iframe.html:
* fast/js/same-origin-subframe-about-blank.html:
* fast/multicol/span/removal-of-multicol-span-crash.html:
* fast/text/international/bidi-neutral-in-mixed-direction-run-crash.html:
* fast/writing-mode/overhanging-float-legend-crash.html:

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@145857 268f45cc-cd09-0410-ab3c-d52691b4dbfc
Unreviewed gardening. Added images for new test.

* platform/chromium-mac-lion/platform/chromium/scrollbars/short-scrollbar-expected.png: Added.
* platform/chromium-mac-snowleopard/platform/chromium/scrollbars/short-scrollbar-expected.png: Added.
* platform/chromium-mac/platform/chromium/scrollbars/short-scrollbar-expected.png: Added.
* platform/chromium-win/platform/chromium/scrollbars/short-scrollbar-expected.png: Added.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@145858 268f45cc-cd09-0410-ab3c-d52691b4dbfc