Adding support for asm.js foreign globals.

test/mjsunit/wasm/asm-wasm.js

 // Copyright 2015 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 EmptyTest() {
   "use asm";
   function caller() {
     empty();
@@ skipping 1062 matching lines @@
   var foreign = new ffi();
 
   var module = _WASMEXP_.instantiateModuleFromAsm(AsmModule.toString(),
                                                   foreign, null);
 
   module.__init__();
   assertEquals(89, module.caller(83, 83.25));
 }
 
 TestForeignFunctionMultipleUse();
+
+
+function TestForeignVariables() {

[aseemgarg, 2016/02/09 02:38:56]

Might want to also write test that uses same foreign variable both as int and
double.

[bradnelson, 2016/02/09 04:55:23]

Done.

+  function AsmModule(stdlib, foreign, buffer) {
+    "use asm";
+
+    var i1 = foreign.foo | 0;
+    var f1 = +foreign.bar;
+
+    function geti() {
+      return i1|0;
+    }
+
+    function getf() {
+      return +f1;
+    }
+
+    return {geti:geti, getf:getf};
+  }
+
+  // Check normal operation.
+  var module = _WASMEXP_.instantiateModuleFromAsm(
+      AsmModule.toString(), {foo: 123, bar: 234}, null);
+  module.__init__();
+  assertEquals(123, module.geti());
+  assertEquals(234, module.getf());
+
+  // Check that undefined values are converted to zero.

[aseemgarg, 2016/02/09 02:38:56]

As discussed, doubles should flow as NaNs. Please fix.

[bradnelson, 2016/02/09 04:55:23]

Done.

+  var module = _WASMEXP_.instantiateModuleFromAsm(
+      AsmModule.toString(), {baz: 678}, null);
+  module.__init__();
+  assertEquals(0, module.geti());
+  assertEquals(0, module.getf());
+
+  // Check that a missing ffi object is safe.
+  var module = _WASMEXP_.instantiateModuleFromAsm(
+      AsmModule.toString());
+  module.__init__();
+  assertEquals(0, module.geti());
+  assertEquals(0, module.getf());
+}
+
+TestForeignVariables();