Changes gl::RenderbufferStorage to rx::RenderbufferImpl

BUG=angle:782

Also eliminates Colorbuffer/DepthStencilBuffer and related friends
and adds the RenderbufferD3D implementation of RenderbufferImpl.

This version fixes problems with the prior CL's handling of
render target serial issuance.

Change-Id: I7ddfbec1097723d7ea6ce93a9c034f941349108a
Reviewed-on: https://chromium-review.googlesource.com/227195
Reviewed-by: Geoff Lang <geofflang@chromium.org>
Tested-by: Shannon Woods <shannonwoods@chromium.org>
diff --git a/src/libGLESv2/ResourceManager.cpp b/src/libGLESv2/ResourceManager.cpp
index 04fa841..35f8783 100644
--- a/src/libGLESv2/ResourceManager.cpp
+++ b/src/libGLESv2/ResourceManager.cpp
@@ -403,7 +403,7 @@
 {
     if (renderbuffer != 0 && !getRenderbuffer(renderbuffer))
     {
-        Renderbuffer *renderbufferObject = new Renderbuffer(renderbuffer, new Colorbuffer(mRenderer, 0, 0, GL_RGBA4, 0));
+        Renderbuffer *renderbufferObject = new Renderbuffer(mRenderer->createRenderbuffer(), renderbuffer);
         mRenderbufferMap[renderbuffer] = renderbufferObject;
         renderbufferObject->addRef();
     }