Bug 1405778. Remove largely unneeded call to nsDisplayBackgroundColor::GetLayerState. r=kats

Text clipping is the only thing we don't handle and it's better to just have this inline.

gfx/thebes/gfxPrefs.h

@@ -538,7 +538,7 @@ private:
   DECL_GFX_PREF(Live, "layers.acceleration.draw-fps.print-histogram",  FPSPrintHistogram, bool, false);
   DECL_GFX_PREF(Live, "layers.acceleration.draw-fps.write-to-file", WriteFPSToFile, bool, false);
   DECL_GFX_PREF(Once, "layers.acceleration.force-enabled",     LayersAccelerationForceEnabledDoNotUseDirectly, bool, false);
-  DECL_OVERRIDE_PREF(Live, "layers.advanced.background-color",        LayersAllowBackgroundColorLayers, gfxPrefs::OverrideBase_WebRender());
+  DECL_GFX_PREF(Live, "layers.advanced.background-color",      LayersAllowBackgroundColorLayers, bool, false);
   DECL_OVERRIDE_PREF(Live, "layers.advanced.background-image",        LayersAllowBackgroundImage, gfxPrefs::OverrideBase_WebRender());
   DECL_GFX_PREF(Live, "layers.advanced.basic-layer.enabled",          LayersAdvancedBasicLayerEnabled, bool, false);
   DECL_OVERRIDE_PREF(Live, "layers.advanced.border-layers",           LayersAllowBorderLayers, gfxPrefs::OverrideBase_WebRender());

layout/painting/nsDisplayList.cpp

@@ -4262,15 +4262,15 @@ nsDisplayBackgroundColor::CreateWebRenderCommands(mozilla::wr::DisplayListBuilde
                                                   mozilla::layers::WebRenderLayerManager* aManager,
                                                   nsDisplayListBuilder* aDisplayListBuilder)
 {
-  ContainerLayerParameters parameter;
-  if (GetLayerState(aDisplayListBuilder, aManager, parameter) != LAYER_ACTIVE) {
-    return false;
-  }
-
   if (mColor == Color()) {
     return true;
   }
 
+  StyleGeometryBox clip = mBackgroundStyle->mImage.mLayers[0].mClip;
+  if (clip == StyleGeometryBox::Text) {
+    return false;
+  }
+
   LayoutDeviceRect bounds = LayoutDeviceRect::FromAppUnits(
         mBackgroundRect, mFrame->PresContext()->AppUnitsPerDevPixel());
   wr::LayoutRect transformedRect = aSc.ToRelativeLayoutRect(bounds);

modules/libpref/init/all.js

@@ -5885,7 +5885,7 @@ pref("layers.mlgpu.enable-on-windows7", true);
 // it to a boolean as appropriate. In particular, do NOT add ifdefs here to
 // turn these on and off, instead use the conditional-pref code in gfxPrefs.h
 // to do that.
-pref("layers.advanced.background-color", 2);
+pref("layers.advanced.background-color", false);
 pref("layers.advanced.background-image", 2);
 pref("layers.advanced.border-layers", 2);
 pref("layers.advanced.boxshadow-inset-layers", 2);