Move FilterIterator and IteratorPair to WTF and reimplement HashMap::keys() and HashMap::values() using IteratorPair
https://bugs.webkit.org/show_bug.cgi?id=126253

Reviewed by Anders Carlsson.

../WebKit2: 

* Shared/APIArray.h:
Update includes and make elementsOfType() a bit easier to read by using a typedef and some
judicial indentation.

* Shared/FilterIterator.h: Moved to WTF.
* Shared/IteratorPair.h: Moved to WTF.
        
* WebKit2.xcodeproj/project.pbxproj:
Remove the two files.

../WTF: 

* GNUmakefile.list.am:
* WTF.vcxproj/WTF.vcxproj:
* WTF.vcxproj/WTF.vcxproj.filters:
* WTF.xcodeproj/project.pbxproj:
* wtf/CMakeLists.txt:
Add new files.

* wtf/HashMap.h:
* wtf/RefPtrHashMap.h:
Remove the old implementation of keys() and values() and replace it with one
that uses IteratorPair.
        
* wtf/FilterIterator.h: Copied from Source/WebKit2/Shared/FilterIterator.h.
* wtf/IteratorPair.h: Copied from Source/WebKit2/Shared/IteratorPair.h.


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@161114 268f45cc-cd09-0410-ab3c-d52691b4dbfc