Bug 1143979 - Use RAII local instead of useless temporary. - r=kamidphish

dom/canvas/WebGLRenderbuffer.cpp

@@ -179,6 +179,8 @@ void
 WebGLRenderbuffer::RenderbufferStorage(GLsizei samples, GLenum internalFormat,
                                        GLsizei width, GLsizei height) const
 {
+    MOZ_ASSERT(mContext->mBoundRenderbuffer == this);
+
     gl::GLContext* gl = mContext->gl;
     MOZ_ASSERT(samples >= 0 && samples <= 256); // Sanity check.
 

dom/canvas/WebGLTexture.cpp

@@ -599,10 +599,10 @@ ClearWithTempFB(WebGLContext* webgl, GLuint tex,
 
     gl::ScopedRenderbuffer rb(gl);
     {
-        gl::ScopedBindRenderbuffer(gl, rb.RB());
-        gl->fRenderbufferStorage(LOCAL_GL_RENDERBUFFER,
-                                 LOCAL_GL_RGBA4,
-                                 width, height);
+        // Only GLES guarantees RGBA4.
+        GLenum format = gl->IsGLES() ? LOCAL_GL_RGBA4 : LOCAL_GL_RGBA8;
+        gl::ScopedBindRenderbuffer rbBinding(gl, rb.RB());
+        gl->fRenderbufferStorage(LOCAL_GL_RENDERBUFFER, format, width, height);
     }
 
     gl->fFramebufferRenderbuffer(LOCAL_GL_FRAMEBUFFER, LOCAL_GL_COLOR_ATTACHMENT0,