servo: Merge #2602 - Don't require root pipeline to match new pipeline (from mbrubeck:revert-root-pipeline-check); r=pcwalton

This reverts 2b0134be7bb8a4372f1a8703b5a1b114e65351f6 because it was not correct for iframes.  Oops.  (Wasn't caught by tests because we still have other crashes preventing iframe testing.)  r? @pcwalton.

Source-Repo: https://github.com/servo/servo
Source-Revision: 1184b500e50123fdcfb6824bed1df6e770b0d0f8

servo/src/components/main/compositing/compositor.rs

@@ -359,7 +359,7 @@ impl IOCompositor {
             }
             _ => {
                 match self.root_pipeline {
-                    Some(ref root_pipeline) if root_pipeline.id == id => {
+                    Some(ref root_pipeline) => {
                         (root_pipeline.clone(), LayerId::null())
                     },
                     _ => fail!("Compositor: Received new layer without initialized pipeline"),