Bug 807151 - Unexport |mozilla| from the |js| namespace; r=Waldo

Clang does not want to allow js::ion::Range and mozilla::Range simultaneously
when we have a |namespace js { using namespace mozilla; }| declaration.

js/src/jsatom.cpp

@@ -36,10 +36,13 @@
 
 #include "vm/String-inl.h"
 
-using namespace mozilla;
 using namespace js;
 using namespace js::gc;
 
+using mozilla::ArrayEnd;
+using mozilla::ArrayLength;
+using mozilla::RangedPtr;
+
 const char *
 js_AtomToPrintableString(JSContext *cx, JSAtom *atom, JSAutoByteString *bytes)
 {