[wasm] Making compare and conditionals more correct.

test/mjsunit/regress/regress-wasm-crbug-599413.js

+// Copyright 2016 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Flags: --expose-wasm
+
+function __f_100() {
+  "use asm";
+  function __f_76() {
+    var __v_39 = 0;
+    outer: while (1) {
+      while (__v_39 == 4294967295) {
+      }
+    }
+  }
+  return {__f_76: __f_76};
+}
+assertThrows(function() {
+  Wasm.instantiateModuleFromAsm(__f_100.toString());
+});