search results management.
https://bugs.webkit.org/show_bug.cgi?id=106834.
<rdar://problem/12597159>

Source/WebCore: 

Reviewed by Simon Fraser.
        
Adding new API to perform text search in WebKit2 without using
the stock UI. The new interface provides all the information
necessary to write a custom UI for search.

Added new TextWebKitAPI test.

* WebCore.exp.in: Added new exported methods.
* editing/Editor.cpp:
(WebCore::Editor::countMatchesForText): Added new parameter to store
all the ranges relative to the matches found.
* editing/Editor.h: Modified the interface of countMatchesForText and removed
the other definition of countMatchesForText with a different signature.
* page/Page.cpp:
(WebCore::Page::findStringMatchingRanges): Added.
(WebCore::Page::markAllMatchesForText): Changed to use the new unified
countMatchesForText.
* page/Page.h:

Source/WebKit/mac: 

Reviewed by Simon Fraser.
        
Adding new API to perform text search in WebKit2 with...