Merge 108574 - REGRESSION (r104060): Web font is not loaded if specified by link element dynamicall…

Merge 108574 - REGRESSION (r104060): Web font is not loaded if specified by link element dynamically inserted
https://bugs.webkit.org/show_bug.cgi?id=79186

Reviewed by Andreas Kling.

Source/WebCore: 

Test: fast/css/font-face-insert-link.html
        
If a dynamically inserted stylesheet contains @font-face rules, we may fail to update the rendering.
        
Before r104060 the style selector was destroyed on every style change, and the font selector along with it.
This is no longer the case and we can't rely on comparing font selector pointers when comparing Fonts
for equality. This patch adds version number to the font selector and checks it in Font::operator==.
The version number is incremented when new font-face rules are added to the font selector.
        
FontFallbackList is an object shared between Fonts so the extra field shouldn't matter much in terms
of memory.

* css/CSSFontSelector.cpp:
(WebCore::CSSFontSelector::CSSFontSelector):
(WebCore::CSSFontSelector::addFontFaceRule):
* css/CSSFontSelector.h:
(CSSFontSelector):
* platform/graphics/Font.cpp:
(WebCore::Font::operator==):
* platform/graphics/FontFallbackList.cpp:
(WebCore::FontFallbackList::FontFallbackList):
(WebCore::FontFallbackList::invalidate):
* platform/graphics/FontFallbackList.h:
(FontFallbackList):
(WebCore::FontFallbackList::fontSelectorVersion):
* platform/graphics/FontSelector.h:
(FontSelector):

LayoutTests: 

* fast/css/font-face-insert-link-expected.txt: Added.
* fast/css/font-face-insert-link.html: Added.
* fast/css/resources/ahem.css: Added.
(@font-face):



TBR=karen@chromium.org
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=109700