[turbofan] Support lazy deopt for truncating store to a typed array.

test/mjsunit/compiler/truncating-store-deopt.js

Index: test/mjsunit/compiler/truncating-store-deopt.js
diff --git a/test/mjsunit/compiler/truncating-store-deopt.js b/test/mjsunit/compiler/truncating-store-deopt.js
new file mode 100644
index 0000000000000000000000000000000000000000..a640caf58347d1341e4aa0f2d26d8c9aa373be0a
--- /dev/null
+++ b/test/mjsunit/compiler/truncating-store-deopt.js
@@ -0,0 +1,28 @@
+// 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: --allow-natives-syntax
+
+function g(a, b, c) {
+  return a + b + c;
+}
+
+var asm = (function Module(global, env, buffer) {
+  "use asm";
+
+  var i32 = new global.Int32Array(buffer);
+
+  // This is not valid asm.js, but we should still generate correct code.
+  function store(x) {
+    return g(1, i32[0] = x, 2);
+  }
+
+  return { store: store };
+})({
+  "Int32Array": Int32Array
+}, {}, new ArrayBuffer(64 * 1024));
+
+var o = { toString : function() { %DeoptimizeFunction(asm.store); return "1"; } }
+
+asm.store(o);