[wasm] Call a runtime function for a MemorySize instruction.

test/mjsunit/wasm/memory-size.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 testMemorySizeZero() {
+  print("testMemorySizeZero()");
+  var builder = new WasmModuleBuilder();
+  builder.addFunction("memory_size", kSig_i_v)
+         .addBody([kExprMemorySize])
+         .exportFunc();
+  var module = builder.instantiate();
+  assertEquals(0, module.exports.memory_size());
+})();
+
+(function testMemorySizeNonZero() {
+  print("testMemorySizeNonZero()");
+  var builder = new WasmModuleBuilder();
+  var size = 11;
+  builder.addMemory(size, size, false);
+  builder.addFunction("memory_size", kSig_i_v)
+         .addBody([kExprMemorySize])
+         .exportFunc();
+  var module = builder.instantiate();
+  assertEquals(size, module.exports.memory_size());
+})();