Bug 931571, part 12 - Add nsDiscriminatedUnion::GetType(). r=froydnj

This is not quite enough to make the data members private because
XPCVariant pokes around to do some JS array stuff.

js/xpconnect/src/XPCVariant.cpp

@@ -274,7 +274,7 @@ bool XPCVariant::InitializeData(JSContext* cx)
         if (!str)
             return false;
 
-        MOZ_ASSERT(mData.mType == nsIDataType::VTYPE_EMPTY,
+        MOZ_ASSERT(mData.GetType() == nsIDataType::VTYPE_EMPTY,
                    "Why do we already have data?");
 
         size_t length = JS_GetStringLength(str);
@@ -645,7 +645,7 @@ XPCVariant::VariantDataToJS(nsIVariant* variant,
 /* readonly attribute uint16_t dataType; */
 NS_IMETHODIMP XPCVariant::GetDataType(uint16_t* aDataType)
 {
-    *aDataType = mData.mType;
+    *aDataType = mData.GetType();
     return NS_OK;
 }
 

xpcom/ds/nsVariant.cpp

@@ -1733,7 +1733,7 @@ nsVariant::~nsVariant()
 NS_IMETHODIMP
 nsVariant::GetDataType(uint16_t* aDataType)
 {
-  *aDataType = mData.mType;
+  *aDataType = mData.GetType();
   return NS_OK;
 }
 

xpcom/ds/nsVariant.h

@@ -35,6 +35,8 @@ public:
 
   void Cleanup();
 
+  uint16_t GetType() const { return mType; }
+
   nsresult ConvertToInt8(uint8_t* aResult) const;
   nsresult ConvertToInt16(int16_t* aResult) const;
   nsresult ConvertToInt32(int32_t* aResult) const;