[EFL][WK2] Add contents,size,changed signal to the ewk_view API

[EFL][WK2] Add contents,size,changed signal to the ewk_view API
https://bugs.webkit.org/show_bug.cgi?id=103094

Reviewed by Kenneth Rohde Christiansen.

This patch emits signal to let applications know contents size.
Applications can use this signal to give some additional behavior such as
minimap, external scroll for quick movement.

* UIProcess/API/efl/EwkViewCallbacks.h: Added contents,size,changed signal.
* UIProcess/API/efl/EwkViewImpl.cpp: Removed dead code.
* UIProcess/API/efl/EwkViewImpl.h: Ditto.
(EwkViewImpl):
* UIProcess/API/efl/ewk_view.h: Added test case.
* UIProcess/API/efl/tests/test_ewk2_view.cpp:
(onContentsSizeChanged):
(TEST_F):
* UIProcess/efl/PageClientDefaultImpl.cpp: Emitted contents,size,changed signal.
(WebKit::PageClientDefaultImpl::didChangeContentsSize):
* UIProcess/efl/PageClientLegacyImpl.cpp: Ditto.
(WebKit::PageClientLegacyImpl::didChangeContentsSize):
* WebProcess/WebCoreSupport/WebChromeClient.cpp:
(WebKit::WebChromeClient::contentsSizeChanged):
Sended DidChangeContentsSize message although TILED_BACKINGSTORE is disabled.

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@136402 268f45cc-cd09-0410-ab3c-d52691b4dbfc