Fix nested unicode-bidi: isolate

Fix nested unicode-bidi: isolate
https://bugs.webkit.org/show_bug.cgi?id=120504

Patch by Myles C. Maxfield <mmaxfield@apple.com> on 2013-09-11
Reviewed by Darin Adler.

Source/WebCore:

When we have a nested isolate renderer if the outer isolate has a text
and this text is not the first child, the isolated chain is not
rendered correctly. This happens because constructBidiRunsForSegment
uses always the first inner isolated renderer as isolated inline
container. This patch fixes the behavior described changing
containingIsolate to find the right isolated container.

Blink: https://chromium.googlesource.com/chromium/blink/+/840a57050eade39dd04dde0c6603e129b783151c
Tests: fast/text/international/unicode-bidi-isolate-nested-first-child-text.html
       fast/text/international/unicode-bidi-isolate-nested-simple.html

* rendering/InlineIterator.h:
(WebCore::containingIsolate):
* rendering/RenderBlockLineLayout.cpp:
(WebCore::constructBidiRunsForSegment):

LayoutTests:

* fast/text/international/unicode-bidi-isolate-nested-first-child-text-expected.html: Added.
* fast/text/international/unicode-bidi-isolate-nested-first-child-text.html: Added.
* fast/text/international/unicode-bidi-isolate-nested-simple-expected.html: Added.
* fast/text/international/unicode-bidi-isolate-nested-simple.html: Added.

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@155554 268f45cc-cd09-0410-ab3c-d52691b4dbfc