#375: M1363423 M1273828 M1364661

browser/base/content/tabbrowser.xml

@@ -2281,7 +2281,7 @@
 
             // update the UI early for responsiveness
             aTab.collapsed = true;
-            this.tabContainer._fillTrailingGap();
+            //this.tabContainer._fillTrailingGap();
             this._blurTab(aTab);
 
             this._removingTabs.splice(this._removingTabs.indexOf(aTab), 1);
@@ -5077,7 +5077,7 @@
               var width = this.mTabstrip.boxObject.width;
               if (width != this.mTabstripWidth) {
                 this.adjustTabstrip();
-                this._fillTrailingGap();
+                //this._fillTrailingGap();
                 this._handleTabSelect();
                 this.mTabstripWidth = width;
               }
@@ -5237,7 +5237,7 @@
           this.adjustTabstrip();
 
           if (tab.getAttribute("selected") == "true") {
-            this._fillTrailingGap();
+            //this._fillTrailingGap();
             this._handleTabSelect();
           } else {
             this._notifyBackgroundTab(tab);

js/src/jsapi.cpp

@@ -6064,19 +6064,67 @@ DescribeScriptedCaller(JSContext* cx, AutoFilename* filename, unsigned* lineno,
     return true;
 }
 
+// Fast path to get the activation to use for GetScriptedCallerGlobal. If this
+// returns false, the fast path didn't work out and the caller has to use the
+// (much slower) NonBuiltinFrameIter path.
+//
+// The optimization here is that we skip Ion-inlined frames and only look at
+// 'outer' frames. That's fine: each activation is tied to a single compartment,
+// so if an activation contains at least one non-self-hosted frame, we can use
+// the activation's global for GetScriptedCallerGlobal. If, however, all 'outer'
+// frames are self-hosted, it's possible Ion inlined a non-self-hosted script,
+// so we must return false and use the slower path.
+static bool
+GetScriptedCallerActivationFast(JSContext* cx, Activation** activation)
+{
+    ActivationIterator activationIter(cx->runtime());
+
+    while (!activationIter.done() && activationIter->cx() != cx)
+        ++activationIter;
+
+    if (activationIter.done()) {
+        *activation = nullptr;
+        return true;
+    }
+
+    *activation = activationIter.activation();
+
+    if (activationIter->isJit()) {
+        for (jit::JitFrameIterator iter(activationIter); !iter.done(); ++iter) {
+            if (iter.isScripted() && !iter.script()->selfHosted())
+                return true;
+        }
+    } else if (activationIter->isInterpreter()) {
+        for (InterpreterFrameIterator iter((*activation)->asInterpreter()); !iter.done(); ++iter) {
+            if (!iter.frame()->script()->selfHosted())
+                return true;
+        }
+    }
+
+    return false;
+}
+
 JS_PUBLIC_API(JSObject*)
 GetScriptedCallerGlobal(JSContext* cx)
 {
-    NonBuiltinFrameIter i(cx);
-    if (i.done())
-        return nullptr;
+    Activation* activation;
+
+    if (GetScriptedCallerActivationFast(cx, &activation)) {
+        if (!activation)
+            return nullptr;
+    } else {
+        NonBuiltinFrameIter i(cx);
+        if (i.done())
+            return nullptr;
+        activation = i.activation();
+    }
 
     // If the caller is hidden, the embedding wants us to return null here so
     // that it can check its own stack (see HideScriptedCaller).
-    if (i.activation()->scriptedCallerIsHidden())
+    if (activation->scriptedCallerIsHidden())
         return nullptr;
 
-    GlobalObject* global = i.activation()->compartment()->maybeGlobal();
+    GlobalObject* global = activation->compartment()->maybeGlobal();
 
     // Noone should be running code in the atoms compartment or running code in
     // a compartment without any live objects, so there should definitely be a

layout/base/FrameLayerBuilder.cpp

@@ -3575,6 +3575,10 @@ PaintedLayerData::AccumulateEventRegions(ContainerState* aState, nsDisplayLayerE
   tmp.Or(mVerticalPanRegion, aEventRegions->VerticalPanRegion()); mVerticalPanRegion = tmp;
 #endif
 
+  // Avoid quadratic performance as a result of the region growing to include
+  // and arbitrarily large number of rects, which can happen on some pages.
+  mMaybeHitRegion.SimplifyOutward(8);
+
   // Calculate scaled versions of the bounds of mHitRegion and mMaybeHitRegion
   // for quick access in FindPaintedLayerFor().
   mScaledHitRegionBounds = aState->ScaleToOutsidePixels(mHitRegion.GetBounds());