remove the duplicated build rules from WebKit.gyp, Tools.gyp

remove the duplicated build rules from WebKit.gyp, Tools.gyp
https://bugs.webkit.org/show_bug.cgi?id=73384

Reviewed by Tony Chang.

Source/WebKit/chromium:

This patch removes the no-longer-necessary conditional logic for
build_webkit_exes_from_webkit_gyp; we now always build the exes
from their own dedicated gyp files.
* WebKit.gyp:
* WebKitUnitTests.gyp:
* gyp_webkit:

Tools:

This patch removes the no-longer-necessary conditional logic for
build_webkit_exes_from_webkit_gyp; we now always build the exes
from their own dedicated gyp files.

* DumpRenderTree/DumpRenderTree.gyp/DumpRenderTree.gyp:

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@105449 268f45cc-cd09-0410-ab3c-d52691b4dbfc