Avoid double hash table lookups in TextureMapperGL
https://bugs.webkit.org/show_bug.cgi?id=114030

Reviewed by Noam Rosenthal.

Use Vector::add() and leverage its returned AddResult value instead of
calling Vector::find() then Vector::set() if the key does not already
exist in the map. This results in a single hash lookup instead of two
in this case.

No new tests, no behavior change.

* platform/graphics/texmap/TextureMapperGL.cpp:
(WebCore::TextureMapperGLData::SharedGLData::getShaderProgram):
(WebCore::TextureMapperGLData::getStaticVBO):
(WebCore::TextureMapperGL::drawUsingCustomFilter):


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@147742 268f45cc-cd09-0410-ab3c-d52691b4dbfc