Bug 833340 - Fix a couple of jittests failing with rooting analysis r=terrence

js/src/jsscope.cpp

@@ -1054,7 +1054,7 @@ JSObject::preventExtensions(JSContext *cx)
      * new dense elements can be added without calling growElements(), which
      * checks isExtensible().
      */
-    if (isNative() && !JSObject::sparsifyDenseElements(cx, self))
+    if (self->isNative() && !JSObject::sparsifyDenseElements(cx, self))
         return false;
 
     return self->setFlag(cx, BaseShape::NOT_EXTENSIBLE, GENERATE_SHAPE);

js/src/vm/String-inl.h

@@ -157,10 +157,10 @@ JSString::readBarrier(JSString *str)
 }
 
 JS_ALWAYS_INLINE bool
-JSString::validateLength(JSContext *cx, size_t length)
+JSString::validateLength(JSContext *maybecx, size_t length)
 {
     if (JS_UNLIKELY(length > JSString::MAX_LENGTH)) {
-        js_ReportAllocationOverflow(cx);
+        js_ReportAllocationOverflow(maybecx);
         return false;
     }
 

js/src/vm/String.cpp

@@ -314,11 +314,9 @@ ConcatStringsMaybeAllowGC(JSContext *cx,
         return left;
 
     size_t wholeLength = leftLen + rightLen;
-    if (!JSString::validateLength(cx, wholeLength)) {
-        if (!allowGC)
-            cx->clearPendingException();
+    JSContext *cxIfCanGC = allowGC ? cx : NULL;
+    if (!JSString::validateLength(cxIfCanGC, wholeLength))
         return NULL;
-    }
 
     if (JSShortString::lengthFits(wholeLength)) {
         JSShortString *str = allowGC ? js_NewGCShortString(cx) : js_TryNewGCShortString(cx);

js/src/vm/String.h

@@ -239,7 +239,7 @@ class JSString : public js::gc::Cell
      * representable by a JSString. An allocation overflow is reported if false
      * is returned.
      */
-    static inline bool validateLength(JSContext *cx, size_t length);
+    static inline bool validateLength(JSContext *maybecx, size_t length);
 
     static void staticAsserts() {
         JS_STATIC_ASSERT(JS_BITS_PER_WORD >= 32);