Remove quirks mode for view-source

The current view-source page uses quirks mode, break-word, and
tables, which is a very slow Layout code path. This CL removes
quirks mode.

Bug: 920571
Change-Id: I011ebd1ef3ab3f0588886342530f3ddaa2468527
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2424574
Auto-Submit: Mason Freed <masonfreed@chromium.org>
Commit-Queue: Koji Ishii <kojii@chromium.org>
Reviewed-by: Koji Ishii <kojii@chromium.org>
Cr-Commit-Position: refs/heads/master@{#809671}

third_party/blink/renderer/core/html/html_view_source_document.cc

@@ -45,9 +45,7 @@ namespace blink {
 HTMLViewSourceDocument::HTMLViewSourceDocument(const DocumentInit& initializer)
     : HTMLDocument(initializer), type_(initializer.GetMimeType()) {
   SetIsViewSource(true);
-
-  // FIXME: Why do view-source pages need to load in quirks mode?
-  SetCompatibilityMode(kQuirksMode);
+  SetCompatibilityMode(kNoQuirksMode);
   LockCompatibilityMode();
 }