Bug 753517 part 1. Make GetParentObject() on CSS declarations return a useful nsINode if possible. r=peterv,dbaron

dom/base/nsDOMClassInfo.cpp

@@ -10190,7 +10190,7 @@ nsCSSStyleDeclSH::PreCreate(nsISupports *nativeObj, JSContext *cx,
   nsICSSDeclaration *declaration = static_cast<nsICSSDeclaration*>(nativeObj);
   nsINode *native_parent = declaration->GetParentObject();
   if (!native_parent) {
-    return NS_ERROR_FAILURE;
+    return nsDOMClassInfo::PreCreate(nativeObj, cx, globalObj, parentObj);
   }
 
   nsresult rv =

layout/style/Rule.h

@@ -10,9 +10,10 @@
 
 #include "nsIStyleRule.h"
 #include "nsIDOMCSSRule.h"
+#include "nsCSSStyleSheet.h"
 
 class nsIStyleSheet;
-class nsCSSStyleSheet;
+class nsIDocument;
 struct nsRuleData;
 template<class T> struct already_AddRefed;
 
@@ -76,6 +77,13 @@ public:
 
   nsCSSStyleSheet* GetStyleSheet() const { return mSheet; }
 
+  // Return the document the rule lives in, if any
+  nsIDocument* GetDocument() const
+  {
+    nsCSSStyleSheet* sheet = GetStyleSheet();
+    return sheet ? sheet->GetDocument() : nullptr;
+  }
+
   virtual void SetStyleSheet(nsCSSStyleSheet* aSheet);
 
   void SetParentRule(GroupRule* aRule) {

layout/style/StyleRule.cpp

@@ -985,7 +985,7 @@ public:
 
   virtual nsINode *GetParentObject()
   {
-    return nullptr;
+    return mRule ? mRule->GetDocument() : nullptr;
   }
 
   friend class css::DOMCSSStyleRule;

layout/style/nsCSSRules.cpp

@@ -1597,7 +1597,7 @@ nsCSSFontFaceStyleDecl::SetPropertyValue(const nsCSSProperty aPropID,
 nsINode*
 nsCSSFontFaceStyleDecl::GetParentObject()
 {
-  return nullptr;
+  return ContainingRule()->GetDocument();
 }
 
 // -------------------------------------------
@@ -1798,6 +1798,12 @@ nsCSSKeyframeStyleDeclaration::DocToUpdate()
   return nullptr;
 }
 
+nsINode*
+nsCSSKeyframeStyleDeclaration::GetParentObject()
+{
+  return mRule ? mRule->GetDocument() : nullptr;
+}
+
 // -------------------------------------------
 // nsCSSKeyframeRule
 //

layout/style/nsCSSRules.h

@@ -307,10 +307,7 @@ public:
   NS_IMETHOD_(nsrefcnt) AddRef();
   NS_IMETHOD_(nsrefcnt) Release();
 
-  virtual nsINode *GetParentObject()
-  {
-    return nullptr;
-  }
+  virtual nsINode* GetParentObject();
 
 protected:
   nsAutoRefCnt mRefCnt;

layout/style/nsCSSStyleSheet.h

@@ -165,6 +165,9 @@ public:
   // Principal() never returns a null pointer.
   nsIPrincipal* Principal() const { return mInner->mPrincipal; }
 
+  // The document this style sheet is associated with.  May be null
+  nsIDocument* GetDocument() const { return mDocument; }
+
   void SetTitle(const nsAString& aTitle) { mTitle = aTitle; }
   void SetMedia(nsMediaList* aMedia);
   void SetOwningNode(nsIDOMNode* aOwningNode) { mOwningNode = aOwningNode; /* Not ref counted */ }