Fix renderbuffer binding for OpenGL ES 1.1.

glBindRenderbufferOES() doesn't require anything except a
non-zero renderbuffer to create a new Renderbuffer object (it is not
required to use GenRenderbuffers before using BindRenderbuffer).
This had been fixed for GLES 3.0 and 2.0, but the same also applies
to GLES 1.1. Note that the Context already properly handles the case
where renderbuffer is zero.

Bug b/25983901

Change-Id: If5e97be8027fca7c97cce5c44d063cd054443700
Reviewed-on: https://swiftshader-review.googlesource.com/17490
Reviewed-by: Nicolas Capens <nicolascapens@google.com>
Reviewed-by: Alexis Hétu <sugoi@google.com>
Tested-by: Nicolas Capens <nicolascapens@google.com>
diff --git a/src/OpenGL/libGLES_CM/libGLES_CM.cpp b/src/OpenGL/libGLES_CM/libGLES_CM.cpp
index f27271c..95c2f24 100644
--- a/src/OpenGL/libGLES_CM/libGLES_CM.cpp
+++ b/src/OpenGL/libGLES_CM/libGLES_CM.cpp
@@ -166,15 +166,9 @@
 
 	if(context)
 	{
-		if(renderbuffer != 0 && !context->getRenderbuffer(renderbuffer))
-		{
-			// [OpenGL ES 2.0.25] Section 4.4.3 page 112
-			// [OpenGL ES 3.0.2] Section 4.4.2 page 201
-			// 'renderbuffer' must be either zero or the name of an existing renderbuffer object of
-			// type 'renderbuffertarget', otherwise an INVALID_OPERATION error is generated.
-			return error(GL_INVALID_OPERATION);
-		}
-
+		// [GL_EXT_framebuffer_object]
+		// If <renderbuffer> is not zero, then the resulting renderbuffer object
+		// is a new state vector, initialized with a zero-sized memory buffer
 		context->bindRenderbuffer(renderbuffer);
 	}
 }