Remove CHECK for same-document provisional frames for M87 beta.

R=nasko@chromium.org

Bug: 1125106
Change-Id: If05f064715add137e16118a08da153d1d5ed0e3e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2465809Reviewed-by: Nasko Oskov <nasko@chromium.org>
Commit-Queue: danakj <danakj@chromium.org>
Cr-Commit-Position: refs/heads/master@{#816752}

content/renderer/render_frame_impl.cc

@@ -3649,7 +3649,9 @@ void RenderFrameImpl::CommitSameDocumentNavigation(
   DCHECK(!commit_params->is_view_source);
   DCHECK(NavigationTypeUtils::IsSameDocument(common_params->navigation_type));
 
-  CHECK(in_frame_tree_);
+  // TODO(danakj): Disabled for M87, but underlying problem exists.
+  // CHECK(in_frame_tree_);
+
   // Unlike a cross-document navigation commit, detach the MHTMLBodyLoaderClient
   // before resetting it. In the case of a cross-document navigation, it's
   // important to ensure *something* commits, even if the original commit