Fixed crashes exposed though fuzzing.

src/runtime.cc

Index: src/runtime.cc
diff --git a/src/runtime.cc b/src/runtime.cc
index 213166a92d48f212d89ad23589505efd7e6a1eea..cf2dcf9f409a64ade32e48b7392537c76312d880 100644
--- a/src/runtime.cc
+++ b/src/runtime.cc
@@ -9449,6 +9449,16 @@ RUNTIME_FUNCTION(MaybeObject*, Runtime_ThrowNotDateError) {
 }
 
 
+RUNTIME_FUNCTION(MaybeObject*, Runtime_ThrowMessage) {
+  HandleScope scope(isolate);
+  ASSERT(args.length() == 2);
+  const char* message =
+    reinterpret_cast<char*>(args[0]) + args.smi_at(1);
+  Handle<Name> message_handle =
+      isolate->factory()->NewStringFromAscii(CStrVector(message));
+  return isolate->Throw(*message_handle);
+}
+
 
 RUNTIME_FUNCTION(MaybeObject*, Runtime_StackGuard) {
   SealHandleScope shs(isolate);