Bug 747815. Use const strings for arguments in DOM bindings. r=peterv

dom/bindings/Codegen.py

@@ -1247,9 +1247,9 @@ def getArgumentConversionTemplate(type, descriptor):
             undefinedBehavior = "eStringify"
 
         return (
-            "  xpc_qsDOMString ${name}(cx, ${argVal}, ${argPtr},\n"
-            "                       xpc_qsDOMString::%s,\n"
-            "                       xpc_qsDOMString::%s);\n"
+            "  const xpc_qsDOMString ${name}(cx, ${argVal}, ${argPtr},\n"
+            "                             xpc_qsDOMString::%s,\n"
+            "                             xpc_qsDOMString::%s);\n"
             "  if (!${name}.IsValid()) {\n"
             "    return false;\n"
             "  }\n" % (nullBehavior, undefinedBehavior))

js/xpconnect/src/XPCQuickStubs.h

@@ -262,7 +262,7 @@ public:
             Ptr()->~implementation_type();
     }
 
-    JSBool IsValid() { return mValid; }
+    JSBool IsValid() const { return mValid; }
 
     implementation_type *Ptr()
     {
@@ -270,12 +270,24 @@ public:
         return reinterpret_cast<implementation_type *>(mBuf);
     }
 
+    const implementation_type *Ptr() const
+    {
+        MOZ_ASSERT(mValid);
+        return reinterpret_cast<const implementation_type *>(mBuf);
+    }
+
     operator interface_type &()
     {
         MOZ_ASSERT(mValid);
         return *Ptr();
     }
 
+    operator const interface_type &() const
+    {
+        MOZ_ASSERT(mValid);
+        return *Ptr();
+    }
+
     /* Enum that defines how JS |null| and |undefined| should be treated.  See
      * the WebIDL specification.  eStringify means convert to the string "null"
      * or "undefined" respectively, via the standard JS ToString() operation;