Revert "Revert "Remove non-const FBO attachment queries.""

Fixed build errors in prior patch.

This reverts commit 34771622d756adc52f02becd7c2b70c717dcc638.

Change-Id: I909b455f2c632a3df7d97149972e167c2adb058f
Reviewed-on: https://chromium-review.googlesource.com/267599
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Tested-by: Jamie Madill <jmadill@chromium.org>
diff --git a/src/libANGLE/validationES.cpp b/src/libANGLE/validationES.cpp
index 71a9007..8019422 100644
--- a/src/libANGLE/validationES.cpp
+++ b/src/libANGLE/validationES.cpp
@@ -498,8 +498,8 @@
         return false;
     }
 
-    gl::Framebuffer *readFramebuffer = context->getState().getReadFramebuffer();
-    gl::Framebuffer *drawFramebuffer = context->getState().getDrawFramebuffer();
+    const gl::Framebuffer *readFramebuffer = context->getState().getReadFramebuffer();
+    const gl::Framebuffer *drawFramebuffer = context->getState().getDrawFramebuffer();
 
     if (!readFramebuffer || !drawFramebuffer)
     {
@@ -597,7 +597,7 @@
                 {
                     if (drawFramebuffer->isEnabledColorAttachment(colorAttachment))
                     {
-                        FramebufferAttachment *attachment = drawFramebuffer->getColorbuffer(colorAttachment);
+                        const FramebufferAttachment *attachment = drawFramebuffer->getColorbuffer(colorAttachment);
                         ASSERT(attachment);
 
                         if (!(attachment->type() == GL_TEXTURE && attachment->getTextureImageIndex().type == GL_TEXTURE_2D) &&