Fixed compilation warnings related to C++ template due to GCC 4.8.

Fixed compilation warnings related to C++ template due to GCC 4.8.

The following warnings have been occurred since GCC was upgraded to 4.8.

/home/abuild/rpmbuild/BUILD/webkit2-efl-123997_0.11.49/Source/WTF/wtf/HashMap.h:137:42: warning: invalid use of incomplete type 'class WTF::HashMap<KeyArg, MappedArg, HashArg, KeyTraitsArg, MappedTraitsArg>' [enabled by default]
         class HashMapKeysProxy : private HashMap {
                                       ^

/home/abuild/rpmbuild/BUILD/webkit2-efl-123997_0.11.49/Source/WTF/wtf/Vector.h:637:44: warning: invalid use of incomplete type ‘class WTF::Vector<T, inlineCapacity>’ [enabled by default]
         class VectorReverseProxy : private Vector {
                                            ^
This can be fixed by moving outside nested classes(HashMapKeyProxy and HashMapValuesProxy), and leave only declaration part inside HashMap. For more details, refer to http://trac.webkit.org/changeset/147345. In case of Vector, the template parameter(T) is added to the base class(Vector) in VectorReverseProxy class for fixing the second warning.

Change-Id: I5302077c1823d9c41650bff1f972ae246d6d6f06