[wasm] Fix receiver conversion for WASM->JS calls.

test/mjsunit/wasm/receiver.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
+
+load("test/mjsunit/wasm/wasm-constants.js");
+load("test/mjsunit/wasm/wasm-module-builder.js");
+
+function testCallImport(func, expected, a, b) {
+  var builder = new WasmModuleBuilder();
+
+  var sig_index = builder.addType(kSig_i_dd);
+  builder.addImport("func", sig_index);
+  builder.addFunction("main", sig_index)
+    .addBody([
+      kExprGetLocal, 0,            // --
+      kExprGetLocal, 1,            // --
+      kExprCallImport, 2, 0])      // --
+    .exportAs("main");
+
+  var main = builder.instantiate({func: func}).exports.main;
+
+  assertEquals(expected, main(a, b));
+}
+
+var global = (function() { return this; })();
+
+function sloppyReceiver(a, b) {
+  assertEquals(global, this);
+  assertEquals(33.3, a);
+  assertEquals(44.4, b);
+  return 11;
+}
+
+function strictReceiver(a, b) {
+  'use strict';
+  assertEquals(undefined, this);
+  assertEquals(55.5, a);
+  assertEquals(66.6, b);
+  return 22;
+}
+
+testCallImport(sloppyReceiver, 11, 33.3, 44.4);
+testCallImport(strictReceiver, 22, 55.5, 66.6);