Bug 1065667 - Fix more bad implicit ctors in layout; r=roc

layout/generic/Selection.h

@@ -215,7 +215,7 @@ public:
   friend struct AutoApplyUserSelectStyle;
   struct MOZ_STACK_CLASS AutoApplyUserSelectStyle
   {
-    AutoApplyUserSelectStyle(Selection* aSelection
+    explicit AutoApplyUserSelectStyle(Selection* aSelection
                              MOZ_GUARD_OBJECT_NOTIFIER_PARAM)
       : mSavedValue(aSelection->mApplyUserSelectStyle)
     {

layout/svg/nsSVGEffects.h

@@ -148,7 +148,7 @@ protected:
 
 struct nsSVGFrameReferenceFromProperty
 {
-  nsSVGFrameReferenceFromProperty(nsIFrame* aFrame)
+  explicit nsSVGFrameReferenceFromProperty(nsIFrame* aFrame)
     : mFrame(aFrame)
     , mFramePresShell(aFrame->PresContext()->PresShell())
   {}