Bug 1331294 - Part 1: Make nsPresContext::HasPendingRestyleOrReflow check nsIPresShell::mNeedStyleFlush instead of asking the RestyleManager for its status. r=bholley

This might delay the resolution of FontFaceSet's ready promise in cases
where we don't delay it now, when we call nsIPresShell::SetNeedRestyle for
something other than posting a restyle.  But from the Font Loading API
spec's point of view, I think this is fine.

MozReview-Commit-ID: AnItzSPnIeB

layout/base/nsPresContext.cpp

@@ -77,7 +77,6 @@
 #include "nsLayoutStylesheetCache.h"
 #include "mozilla/StyleSheet.h"
 #include "mozilla/StyleSheetInlines.h"
-#include "mozilla/ServoRestyleManagerInlines.h"
 #include "mozilla/Telemetry.h"
 #include "mozilla/dom/Performance.h"
 #include "mozilla/dom/PerformanceTiming.h"
@@ -2779,8 +2778,8 @@ nsPresContext::NotifyFontFaceSetOnRefresh()
 bool
 nsPresContext::HasPendingRestyleOrReflow()
 {
-  return (mRestyleManager && mRestyleManager->HasPendingRestyles()) ||
-         PresShell()->HasPendingReflow();
+  nsIPresShell* shell = PresShell();
+  return shell->NeedStyleFlush() || shell->HasPendingReflow();
 }
 
 void

layout/style/test/test_font_loading_api.html

@@ -162,6 +162,10 @@ function awaitRefresh() {
   return awaitOneRefresh().then(awaitOneRefresh);
 }
 
+function flushStyles() {
+  getComputedStyle(document.body).color;
+}
+
 function runTest() {
   // Document and window from inside the display:none iframe.
   var nframe = document.getElementById("n");
@@ -956,6 +960,7 @@ function runTest() {
     is(document.fonts.status, "loading", "FontFaceSet.status after adding a loading FontFace (TEST 32)");
 
     document.fonts.clear();
+    flushStyles();
 
     is(document.fonts.status, "loaded", "FontFaceSet.status after clearing (TEST 32)");