[wasm] Create a proper map for functions created from WASM.

test/mjsunit/wasm/function-prototype.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 TestFunctionPrototype() {
+  var builder = new WasmModuleBuilder();
+
+  builder.addFunction("nine", [kAstI32])
+    .addBody([kExprI8Const, 9])
+    .exportFunc();
+
+  var func = builder.instantiate().exports.nine;
+
+  // Check type and existence of prototype
+  assertEquals("function", typeof func.apply);
+  assertTrue(func.prototype != undefined);
+  assertEquals("nine", func.name);
+  assertEquals(undefined, func.displayName);
+
+  // Check that .apply() works.
+  assertEquals(9, func.apply([]));
+  assertEquals(9, func.apply([1]));
+  assertEquals(9, func.apply([2, 3]));
+  assertEquals(9, func.apply([6, 7, 9, 9]));
+
+  // TODO(titzer): assertEquals(1, func.length);
+
+  // Check we don't crash when converting to a string.
+  print(func.toString());
+})();