Backed out 2 changesets (bug 1356317) for frequent Win7 debug "Assertion failure: !mCompositeDC"

Backed out changeset d0cdeb6ffaeb (bug 1356317)
Backed out changeset 698042ea9555 (bug 1356317)

MozReview-Commit-ID: GUNfDlWpg4p

browser/components/extensions/ExtensionPopups.jsm

@@ -421,9 +421,6 @@ class ViewPopup extends BasePopup {
     // be swapped with the browser in the real panel when it's ready.
     let panel = document.createElement("panel");
     panel.setAttribute("type", "arrow");
-    if (extension.remote) {
-      panel.setAttribute("remote", "true");
-    }
     document.getElementById("mainPopupSet").appendChild(panel);
 
     super(extension, panel, popupURL, browserStyle, fixedWidth, blockParser);

widget/windows/nsWindow.cpp

@@ -7170,6 +7170,19 @@ nsWindow::IsPopup()
   return mWindowType == eWindowType_popup;
 }
 
+bool
+nsWindow::ShouldUseOffMainThreadCompositing()
+{
+  // We don't currently support using an accelerated layer manager with
+  // transparent windows so don't even try. I'm also not sure if we even
+  // want to support this case. See bug 593471
+  if (!(HasRemoteContent() && gIsPopupCompositingEnabled) && mTransparencyMode == eTransparencyTransparent) {
+    return false;
+  }
+
+  return nsBaseWidget::ShouldUseOffMainThreadCompositing();
+}
+
 void
 nsWindow::WindowUsesOMTC()
 {

widget/windows/nsWindow.h

@@ -301,6 +301,7 @@ public:
   bool                    const DestroyCalled() { return mDestroyCalled; }
 
   bool IsPopup();
+  virtual bool ShouldUseOffMainThreadCompositing() override;
 
   const IMEContext& DefaultIMC() const { return mDefaultIMC; }