Add support for the remaining ES3 framebuffer attachment parameter queries.

src/libGLESv2/Framebuffer.cpp

@@ -269,6 +269,11 @@ Renderbuffer *Framebuffer::getStencilbuffer() const
     return mStencilbuffer.get();
 }
 
+Renderbuffer *Framebuffer::getDepthStencilBuffer() const
+{
+    return (mDepthbuffer.id() == mStencilbuffer.id()) ? mDepthbuffer.get() : NULL;
+}
+
 Renderbuffer *Framebuffer::getDepthOrStencilbuffer() const
 {
     Renderbuffer *depthstencilbuffer = mDepthbuffer.get();

src/libGLESv2/Framebuffer.h

@@ -49,6 +49,7 @@ class Framebuffer
     Renderbuffer *getColorbuffer(unsigned int colorAttachment) const;
     Renderbuffer *getDepthbuffer() const;
     Renderbuffer *getStencilbuffer() const;
+    Renderbuffer *getDepthStencilBuffer() const;
     Renderbuffer *getDepthOrStencilbuffer() const;
     Renderbuffer *getReadColorbuffer() const;
     GLenum getReadColorbufferType() const;