Remove NullPointerException.

runtime/vm/exceptions.cc

Index: runtime/vm/exceptions.cc
diff --git a/runtime/vm/exceptions.cc b/runtime/vm/exceptions.cc
index fc2e2c9e70d620e99d57f29d413b280a2e1ca2e5..479ad64437e836f83aa2a82f8492a484359eebfb 100644
--- a/runtime/vm/exceptions.cc
+++ b/runtime/vm/exceptions.cc
@@ -144,7 +144,7 @@ static void ThrowExceptionHelper(const Instance& incoming_exception,
   Instance& exception = Instance::Handle(incoming_exception.raw());
   if (exception.IsNull()) {
     GrowableArray<const Object*> arguments;
-    exception ^= Exceptions::Create(Exceptions::kNullPointer, arguments);
+    exception ^= Exceptions::Create(Exceptions::kNullThrown, arguments);
   }
   uword handler_pc = 0;
   uword handler_sp = 0;
@@ -427,18 +427,14 @@ RawObject* Exceptions::Create(
       library = Library::CoreLibrary();
       class_name = Symbols::New("InternalError");
       break;
-    case kNullPointer:
+    case kNullThrown:
       library = Library::CoreLibrary();
-      class_name = Symbols::New("NullPointerException");
+      class_name = Symbols::New("NullThrownError");
       break;
     case kIllegalJSRegExp:
       library = Library::CoreLibrary();
       class_name = Symbols::New("IllegalJSRegExpException");
       break;
-    case kArgumentError:
-      library = Library::CoreLibrary();
-      class_name = Symbols::New("ArgumentError");
-      break;
     case kIsolateSpawn:
       library = Library::IsolateLibrary();
       class_name = Symbols::New("IsolateSpawnException");