Allow GL_TEXTURE_RECTANGLE_ARB to be the destination target for copyTextureCHROMIUM.

gpu/command_buffer/service/texture_manager.cc

Index: gpu/command_buffer/service/texture_manager.cc
diff --git a/gpu/command_buffer/service/texture_manager.cc b/gpu/command_buffer/service/texture_manager.cc
index 1bce4948bab4498d66e1d86e61a57243830a66c7..8b1bbd0bb633a5c83bf2454e9caffad287e496c3 100644
--- a/gpu/command_buffer/service/texture_manager.cc
+++ b/gpu/command_buffer/service/texture_manager.cc
@@ -1929,14 +1929,7 @@ bool TextureManager::ValidateTexImage(
         error_state, function_name, args.target, "target");
     return false;
   }
-  // TODO(ccameron): Add a separate texture from |texture_target| for
-  // [Compressed]Tex[Sub]Image2D and related functions.

[erikchen, 2015/12/30 22:08:00]

I removed this to get my unit test to work. It's not clear to me why this is
necessary and correct, even when reading the the CL where it was introduced:
https://codereview.chromium.org/1376633002/

Perhaps someone with more experience could comment?

-  // http://crbug.com/536854
-  if (args.target == GL_TEXTURE_RECTANGLE_ARB) {
-    ERRORSTATE_SET_GL_ERROR_INVALID_ENUM(
-        error_state, function_name, args.target, "target");
-    return false;
-  }
+
   if (!ValidateTextureParameters(
       error_state, function_name, args.format, args.type,
       args.internal_format, args.level)) {