The string returned from CSSStyleDeclaration::removeProperty() should only contain the old value, not the property name.

content/html/content/src/nsGenericHTMLElement.cpp

@@ -156,14 +156,20 @@ nsDOMCSSAttributeDeclaration::RemoveProperty(const nsString& aPropertyName,
 
     nsCSSProperty prop = nsCSSProps::LookupProperty(aPropertyName);
     nsCSSValue val;
-    rv = decl->RemoveProperty(prop, val);
-    if (NS_FAILED(rv))
-      return rv;
 
-    val.ToString(aReturn, prop);
+    rv = decl->RemoveProperty(prop, val);
+
+    if (NS_SUCCEEDED(rv)) {
+      // We pass in eCSSProperty_UNKNOWN here so that we don't get the
+      // property name in the return string.
+      val.ToString(aReturn, eCSSProperty_UNKNOWN);
+    } else {
+      // If we tried to remove an invalid property or a property that wasn't
+      //  set we simply return success and an empty string
+      rv = NS_OK;
+    }
 
     if (doc) {
-
       doc->AttributeChanged(mContent, kNameSpaceID_None, nsHTMLAtoms::style,
                             hint);
       doc->EndUpdate();

content/html/style/src/nsCSSStyleRule.cpp

@@ -830,10 +830,16 @@ DOMCSSDeclarationImpl::RemoveProperty(const nsString& aPropertyName,
     nsCSSValue val;
 
     rv = decl->RemoveProperty(prop, val);
-    if (NS_FAILED(rv))
-      return rv;
 
-    val.ToString(aReturn, prop);
+    if (NS_SUCCEEDED(rv)) {
+      // We pass in eCSSProperty_UNKNOWN here so that we don't get the
+      // property name in the return string.
+      val.ToString(aReturn, eCSSProperty_UNKNOWN);
+    } else {
+      // If we tried to remove an invalid property or a property that wasn't 
+      //  set we simply return success and an empty string
+      rv = NS_OK;
+    }
   }
 
   return rv;

layout/html/content/src/nsGenericHTMLElement.cpp

@@ -156,14 +156,20 @@ nsDOMCSSAttributeDeclaration::RemoveProperty(const nsString& aPropertyName,
 
     nsCSSProperty prop = nsCSSProps::LookupProperty(aPropertyName);
     nsCSSValue val;
-    rv = decl->RemoveProperty(prop, val);
-    if (NS_FAILED(rv))
-      return rv;
 
-    val.ToString(aReturn, prop);
+    rv = decl->RemoveProperty(prop, val);
+
+    if (NS_SUCCEEDED(rv)) {
+      // We pass in eCSSProperty_UNKNOWN here so that we don't get the
+      // property name in the return string.
+      val.ToString(aReturn, eCSSProperty_UNKNOWN);
+    } else {
+      // If we tried to remove an invalid property or a property that wasn't
+      //  set we simply return success and an empty string
+      rv = NS_OK;
+    }
 
     if (doc) {
-
       doc->AttributeChanged(mContent, kNameSpaceID_None, nsHTMLAtoms::style,
                             hint);
       doc->EndUpdate();

layout/html/style/src/nsCSSStyleRule.cpp

@@ -830,10 +830,16 @@ DOMCSSDeclarationImpl::RemoveProperty(const nsString& aPropertyName,
     nsCSSValue val;
 
     rv = decl->RemoveProperty(prop, val);
-    if (NS_FAILED(rv))
-      return rv;
 
-    val.ToString(aReturn, prop);
+    if (NS_SUCCEEDED(rv)) {
+      // We pass in eCSSProperty_UNKNOWN here so that we don't get the
+      // property name in the return string.
+      val.ToString(aReturn, eCSSProperty_UNKNOWN);
+    } else {
+      // If we tried to remove an invalid property or a property that wasn't 
+      //  set we simply return success and an empty string
+      rv = NS_OK;
+    }
   }
 
   return rv;

layout/style/nsCSSStyleRule.cpp

@@ -830,10 +830,16 @@ DOMCSSDeclarationImpl::RemoveProperty(const nsString& aPropertyName,
     nsCSSValue val;
 
     rv = decl->RemoveProperty(prop, val);
-    if (NS_FAILED(rv))
-      return rv;
 
-    val.ToString(aReturn, prop);
+    if (NS_SUCCEEDED(rv)) {
+      // We pass in eCSSProperty_UNKNOWN here so that we don't get the
+      // property name in the return string.
+      val.ToString(aReturn, eCSSProperty_UNKNOWN);
+    } else {
+      // If we tried to remove an invalid property or a property that wasn't 
+      //  set we simply return success and an empty string
+      rv = NS_OK;
+    }
   }
 
   return rv;