[wasm] Add a magic word and a version number to the binary.

test/mjsunit/wasm/start-function.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");
 
 function instantiate(sig, body) {
   var module = new Array();
   module = module.concat([
+    // -- header
+    kWasmH0, kWasmH1, kWasmH2, kWasmH3,
+    kWasmV0, kWasmV1, kWasmV2, kWasmV3
+  ]);
+  module = module.concat([
     // -- signatures
     kDeclSignatures, 1,
   ]);
   module = module.concat(sig);
   module = module.concat([
     // -- functions
     kDeclFunctions, 1,
     0,                 // decl flags
     0, 0,              // signature
     body.length, 0,    // body size
@@ skipping 34 matching lines @@
 assertVerifies([0, kAstStmt], [kExprNop]);
 assertVerifies([0, kAstI32], [kExprI8Const, 0]);
 
 // Arguments aren't allow to start functions.
 assertFails([1, kAstI32, kAstI32], [kExprGetLocal, 0]);
 assertFails([2, kAstI32, kAstI32, kAstF32], [kExprGetLocal, 0]);
 assertFails([3, kAstI32, kAstI32, kAstF32, kAstF64], [kExprGetLocal, 0]);
 
 (function testInvalidIndex() {
   var kBodySize = 1;
-  var data = bytes(
+  var data = bytesWithHeader(
     // -- signatures
     kDeclSignatures, 1,
     0, kAstStmt,
     // -- functions
     kDeclFunctions, 1,
     0,                 // decl flags
     0, 0,              // signature
     kBodySize, 0,      // body size
     kExprNop,          // body
     // -- declare start function
     kDeclStartFunction,
     1
   );
 
   assertThrows(function() { _WASMEXP_.instantiateModule(data); });
 })();
 
 
 (function testTwoStartFuncs() {
   var kBodySize = 1;
-  var data = bytes(
+  var data = bytesWithHeader(
     // -- signatures
     kDeclSignatures, 1,
     0, kAstStmt,
     // -- functions
     kDeclFunctions, 1,
     0,                 // decl flags
     0, 0,              // signature
     kBodySize, 0,      // body size
     kExprNop,          // body
     // -- declare start function
     kDeclStartFunction,
     0,
     // -- declare start function
     kDeclStartFunction,
     0
   );
 
   assertThrows(function() { _WASMEXP_.instantiateModule(data); });
 })();
 
 
 (function testRun() {
   var kBodySize = 6;
 
-  var data = bytes(
+  var data = bytesWithHeader(
     kDeclMemory,
     12, 12, 1,                  // memory
     // -- signatures
     kDeclSignatures, 1,
     0, kAstStmt,
     // -- start function
     kDeclFunctions, 1,
     0,                          // decl flags
     0, 0,                       // signature
     kBodySize, 0,               // code size
     // -- start body
     kExprI32StoreMem, 0, kExprI8Const, 0, kExprI8Const, 77,
     // -- declare start function
     kDeclStartFunction,
     0
   );
 
   var module = _WASMEXP_.instantiateModule(data);
   var memory = module.memory;
   var view = new Int8Array(memory);
   assertEquals(77, view[0]);
 })();
 
 (function testStartFFI() {
   var kBodySize = 2;
-  var kNameOffset = 4 + 9 + 7 + 3;
+  var kNameOffset = kHeaderSize + 4 + 9 + 7 + 3;
 
-  var data = bytes(
+  var data = bytesWithHeader(
     // -- signatures
     kDeclSignatures, 1,
     0, kAstStmt,
     // -- imported function
     kDeclFunctions, 2,
     kDeclFunctionImport | kDeclFunctionName,     // decl flags
     0, 0,                       // signature
     kNameOffset, 0, 0, 0,
     // -- start function
     0,                          // decl flags
@@ skipping 12 matching lines @@
   var ffi = new Object();
   ffi.foo = function() {
     print("we ranned at stert!");
     ranned = true;
   }
   var module = _WASMEXP_.instantiateModule(data, ffi);
   var memory = module.memory;
   var view = new Int8Array(memory);
   assertTrue(ranned);
 })();