[asm.js] Fix checking of "fround" in parameter annotation.

R=clemensh@chromium.org
TEST=mjsunit/asm/regress-718745
BUG=chromium:718745

Change-Id: I4d31e90d7a2bbb1d07ce946682a95582f63c7e27
Reviewed-on: https://chromium-review.googlesource.com/497469Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#45134}

src/asmjs/asm-parser.cc

@@ -833,7 +833,8 @@ void AsmJsParser::ValidateFunctionParams(std::vector<AsmType*>* params) {
       info->index = static_cast<uint32_t>(params->size());
       params->push_back(AsmType::Double());
     } else {
-      if (!GetVarInfo(Consume())->type->IsA(stdlib_fround_)) {
+      if (!scanner_.IsGlobal() ||
+          !GetVarInfo(Consume())->type->IsA(stdlib_fround_)) {
         FAIL("Expected fround");
       }
       EXPECT_TOKEN('(');

test/mjsunit/asm/regress-718745.js

+// Copyright 2017 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.
+
+function Module(stdlib) {
+  "use asm";
+  var fround = stdlib.Math.fround;
+  function f(a) {
+    a = (fround(a));
+  }
+  return { f:f };
+}
+Module(this).f();