[wasm] mjsunit support for I32 globals and test

test/mjsunit/wasm/instantiate-module-basic.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
 
 load("test/mjsunit/wasm/wasm-constants.js");
 load("test/mjsunit/wasm/wasm-module-builder.js");
 
 let kReturnValue = 117;
@@ skipping 135 matching lines @@
                                     writer: (x)=>outval_1 = x }, mem_1);
   var i2 = new WebAssembly.Instance(module, {some_value: () => 2,
                                     writer: (x)=>outval_2 = x }, mem_2);
 
   assertEquals(43, i1.exports.main(0));
   assertEquals(1002, i2.exports.main(0));
 
   assertEquals(42, outval_1);
   assertEquals(1000, outval_2);
 })();
+
+(function GlobalsArePrivateToTheInstance() {
+  var builder = new WasmModuleBuilder();
+  builder.addGlobal(kAstI32);
+  builder.addFunction("read", kSig_i_v)
+    .addBody([
+      kExprGetGlobal, 0])
+    .exportFunc();
+
+  builder.addFunction("write", kSig_v_i)
+    .addBody([
+      kExprGetLocal, 0,
+      kExprSetGlobal, 0])
+    .exportFunc();
+
+  var module = new WebAssembly.Module(builder.toBuffer());
+  var i1 = new WebAssembly.Instance(module);
+  var i2 = new WebAssembly.Instance(module);
+  i1.exports.write(1);
+  i2.exports.write(2);
+  assertEquals(1, i1.exports.read());
+  assertEquals(2, i2.exports.read());
+})();