diff --git a/content/base/public/nsIContent.h b/content/base/public/nsIContent.h
index 8ff06e2f79ae..40e00bb87c6d 100644
--- a/content/base/public/nsIContent.h
+++ b/content/base/public/nsIContent.h
@@ -74,9 +74,9 @@ enum nsLinkState {
 };
 
 // IID for the nsIContent interface
-#define NS_ICONTENT_IID       \
-{ 0xdec4b381, 0xa3fc, 0x402b, \
- { 0x83, 0x96, 0x0a, 0x7b, 0x37, 0x52, 0xcf, 0x70 } }
+#define NS_ICONTENT_IID \
+{ 0xb651e0a7, 0x1471, 0x49cc, \
+  { 0xb4, 0xe1, 0xc2, 0xca, 0x01, 0xfe, 0xb7, 0x80 } }
 
 /**
  * A node of content in a document's content model. This interface
@@ -753,18 +753,12 @@ public:
    * have the parser pass true.  See nsHTMLInputElement.cpp and
    * nsHTMLContentSink::MakeContentObject().
    *
-   * It is ok to ignore an error returned from this function.
-   *
-   * This means that implementations will have to deal with returned error
-   * codes being ignored.
-   *
    * @param aHaveNotified Whether there has been a
    *        ContentInserted/ContentAppended notification for this content node
    *        yet.
    */
-  virtual nsresult DoneAddingChildren(bool aHaveNotified)
+  virtual void DoneAddingChildren(bool aHaveNotified)
   {
-    return NS_OK;
   }
 
   /**
diff --git a/content/html/content/src/nsHTMLObjectElement.cpp b/content/html/content/src/nsHTMLObjectElement.cpp
index b984b8d30d8c..7da2d1ad6a6f 100644
--- a/content/html/content/src/nsHTMLObjectElement.cpp
+++ b/content/html/content/src/nsHTMLObjectElement.cpp
@@ -129,7 +129,7 @@ public:
 
   virtual bool IsDisabled() const { return false; }
 
-  virtual nsresult DoneAddingChildren(bool aHaveNotified);
+  virtual void DoneAddingChildren(bool aHaveNotified);
   virtual bool IsDoneAddingChildren();
 
   virtual bool ParseAttribute(PRInt32 aNamespaceID,
@@ -200,7 +200,7 @@ nsHTMLObjectElement::IsDoneAddingChildren()
   return mIsDoneAddingChildren;
 }
 
-nsresult
+void
 nsHTMLObjectElement::DoneAddingChildren(bool aHaveNotified)
 {
   mIsDoneAddingChildren = true;
@@ -210,7 +210,6 @@ nsHTMLObjectElement::DoneAddingChildren(bool aHaveNotified)
   if (IsInDoc()) {
     StartObjectLoad(aHaveNotified);
   }
-  return NS_OK;
 }
 
 NS_IMPL_CYCLE_COLLECTION_CLASS(nsHTMLObjectElement)
diff --git a/content/html/content/src/nsHTMLSelectElement.cpp b/content/html/content/src/nsHTMLSelectElement.cpp
index 6725d4db7afd..c137829d8329 100644
--- a/content/html/content/src/nsHTMLSelectElement.cpp
+++ b/content/html/content/src/nsHTMLSelectElement.cpp
@@ -1443,7 +1443,7 @@ nsHTMLSelectElement::UnsetAttr(PRInt32 aNameSpaceID, nsIAtom* aAttribute,
   return rv;
 }
 
-nsresult
+void
 nsHTMLSelectElement::DoneAddingChildren(bool aHaveNotified)
 {
   mIsDoneAddingChildren = true;
@@ -1480,8 +1480,6 @@ nsHTMLSelectElement::DoneAddingChildren(bool aHaveNotified)
   }
 
   mDefaultSelectionSet = true;
-
-  return NS_OK;
 }
 
 bool
diff --git a/content/html/content/src/nsHTMLSelectElement.h b/content/html/content/src/nsHTMLSelectElement.h
index 16b96d81f25b..3c0f9b64beb0 100644
--- a/content/html/content/src/nsHTMLSelectElement.h
+++ b/content/html/content/src/nsHTMLSelectElement.h
@@ -398,7 +398,7 @@ public:
   virtual nsresult UnsetAttr(PRInt32 aNameSpaceID, nsIAtom* aAttribute,
                              bool aNotify);
   
-  virtual nsresult DoneAddingChildren(bool aHaveNotified);
+  virtual void DoneAddingChildren(bool aHaveNotified);
   virtual bool IsDoneAddingChildren() {
     return mIsDoneAddingChildren;
   }
diff --git a/content/html/content/src/nsHTMLSharedObjectElement.cpp b/content/html/content/src/nsHTMLSharedObjectElement.cpp
index 438c090cdec2..0be91ade3e2a 100644
--- a/content/html/content/src/nsHTMLSharedObjectElement.cpp
+++ b/content/html/content/src/nsHTMLSharedObjectElement.cpp
@@ -127,7 +127,7 @@ public:
   virtual bool IsHTMLFocusable(bool aWithMouse, bool *aIsFocusable, PRInt32 *aTabIndex);
   virtual PRUint32 GetDesiredIMEState();
 
-  virtual nsresult DoneAddingChildren(bool aHaveNotified);
+  virtual void DoneAddingChildren(bool aHaveNotified);
   virtual bool IsDoneAddingChildren();
 
   virtual bool ParseAttribute(PRInt32 aNamespaceID,
@@ -215,7 +215,7 @@ nsHTMLSharedObjectElement::IsDoneAddingChildren()
   return mIsDoneAddingChildren;
 }
 
-nsresult
+void
 nsHTMLSharedObjectElement::DoneAddingChildren(bool aHaveNotified)
 {
   if (!mIsDoneAddingChildren) {
@@ -227,8 +227,6 @@ nsHTMLSharedObjectElement::DoneAddingChildren(bool aHaveNotified)
       StartObjectLoad(aHaveNotified);
     }
   }
-
-  return NS_OK;
 }
 
 NS_IMPL_CYCLE_COLLECTION_CLASS(nsHTMLSharedObjectElement)
diff --git a/content/html/content/src/nsHTMLTextAreaElement.cpp b/content/html/content/src/nsHTMLTextAreaElement.cpp
index fbfcee1a8c94..b76ba838ae5b 100644
--- a/content/html/content/src/nsHTMLTextAreaElement.cpp
+++ b/content/html/content/src/nsHTMLTextAreaElement.cpp
@@ -201,7 +201,7 @@ public:
 
   virtual bool IsHTMLFocusable(bool aWithMouse, bool *aIsFocusable, PRInt32 *aTabIndex);
 
-  virtual nsresult DoneAddingChildren(bool aHaveNotified);
+  virtual void DoneAddingChildren(bool aHaveNotified);
   virtual bool IsDoneAddingChildren();
 
   virtual nsresult Clone(nsINodeInfo *aNodeInfo, nsINode **aResult) const;
@@ -775,7 +775,7 @@ nsHTMLTextAreaElement::PostHandleEvent(nsEventChainPostVisitor& aVisitor)
   return NS_OK;
 }
 
-nsresult
+void
 nsHTMLTextAreaElement::DoneAddingChildren(bool aHaveNotified)
 {
   if (!mValueChanged) {
@@ -790,8 +790,6 @@ nsHTMLTextAreaElement::DoneAddingChildren(bool aHaveNotified)
   }
 
   mDoneAddingChildren = true;
-
-  return NS_OK;
 }
 
 bool
diff --git a/content/html/content/src/nsHTMLTitleElement.cpp b/content/html/content/src/nsHTMLTitleElement.cpp
index b33fd0f97c14..65affa4d3d2f 100644
--- a/content/html/content/src/nsHTMLTitleElement.cpp
+++ b/content/html/content/src/nsHTMLTitleElement.cpp
@@ -84,7 +84,7 @@ public:
   virtual void UnbindFromTree(bool aDeep = true,
                               bool aNullParent = true);
 
-  virtual nsresult DoneAddingChildren(bool aHaveNotified);
+  virtual void DoneAddingChildren(bool aHaveNotified);
 
   virtual nsXPCClassInfo* GetClassInfo();
 private:
@@ -200,13 +200,12 @@ nsHTMLTitleElement::UnbindFromTree(bool aDeep, bool aNullParent)
   nsGenericHTMLElement::UnbindFromTree(aDeep, aNullParent);
 }
 
-nsresult
+void
 nsHTMLTitleElement::DoneAddingChildren(bool aHaveNotified)
 {
   if (!aHaveNotified) {
     SendTitleChangeEvent(false);
   }
-  return NS_OK;
 }
 
 void
diff --git a/content/svg/content/src/nsSVGTitleElement.cpp b/content/svg/content/src/nsSVGTitleElement.cpp
index 2bfd16730340..f1117b495fdc 100644
--- a/content/svg/content/src/nsSVGTitleElement.cpp
+++ b/content/svg/content/src/nsSVGTitleElement.cpp
@@ -77,7 +77,7 @@ public:
   virtual void UnbindFromTree(bool aDeep = true,
                               bool aNullParent = true);
 
-  virtual nsresult DoneAddingChildren(bool aHaveNotified);
+  virtual void DoneAddingChildren(bool aHaveNotified);
 
   virtual nsXPCClassInfo* GetClassInfo();
 private:
@@ -180,13 +180,12 @@ nsSVGTitleElement::UnbindFromTree(bool aDeep, bool aNullParent)
   nsSVGTitleElementBase::UnbindFromTree(aDeep, aNullParent);
 }
 
-nsresult
+void
 nsSVGTitleElement::DoneAddingChildren(bool aHaveNotified)
 {
   if (!aHaveNotified) {
     SendTitleChangeEvent(false);
   }
-  return NS_OK;
 }
 
 void
diff --git a/content/xtf/src/nsXTFElementWrapper.cpp b/content/xtf/src/nsXTFElementWrapper.cpp
index c7613849ab17..38285d285215 100644
--- a/content/xtf/src/nsXTFElementWrapper.cpp
+++ b/content/xtf/src/nsXTFElementWrapper.cpp
@@ -518,13 +518,11 @@ nsXTFElementWrapper::BeginAddingChildren()
     GetXTFElement()->BeginAddingChildren();
 }
 
-nsresult
+void
 nsXTFElementWrapper::DoneAddingChildren(bool aHaveNotified)
 {
   if (mNotificationMask & nsIXTFElement::NOTIFY_DONE_ADDING_CHILDREN)
     GetXTFElement()->DoneAddingChildren();
-
-  return NS_OK;
 }
 
 already_AddRefed<nsINodeInfo>
diff --git a/content/xtf/src/nsXTFElementWrapper.h b/content/xtf/src/nsXTFElementWrapper.h
index 3d2a1e4c09c5..0d1c44b330d0 100644
--- a/content/xtf/src/nsXTFElementWrapper.h
+++ b/content/xtf/src/nsXTFElementWrapper.h
@@ -111,7 +111,7 @@ public:
   virtual nsEventStates IntrinsicState() const;
 
   virtual void BeginAddingChildren();
-  virtual nsresult DoneAddingChildren(bool aHaveNotified);
+  virtual void DoneAddingChildren(bool aHaveNotified);
 
   virtual nsIAtom *GetClassAttributeName() const;
   virtual const nsAttrValue* DoGetClasses() const;