[turbofan] Truncation of Bit/Word8/16 to Word32 is a no-op.

test/mjsunit/compiler/regress-445859.js

Index: test/mjsunit/compiler/regress-445859.js
diff --git a/test/mjsunit/compiler/regress-445267.js b/test/mjsunit/compiler/regress-445859.js
similarity index 56%
copy from test/mjsunit/compiler/regress-445267.js
copy to test/mjsunit/compiler/regress-445859.js
index 465168b6e87ae6d49696d9e67c06a7bb982ace57..256af3eeeb44d535d2d35db7908efcd3dc6a1ed1 100644
--- a/test/mjsunit/compiler/regress-445267.js
+++ b/test/mjsunit/compiler/regress-445859.js
@@ -2,15 +2,10 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-var foo = (function Module(stdlib, foreign, heap) {
+var foo = (function Module(global, env, buffer) {
   "use asm";
-  var MEM16 = new stdlib.Int16Array(heap);
-  function foo(i) {
-    i = i|0;
-    i = MEM16[i + 2147483650 >> 1]|0;
-    return i;
-  }
+  var i8 = new global.Int8Array(buffer);
+  function foo() { i8[0] += 4294967295; }
   return { foo: foo };
 })(this, {}, new ArrayBuffer(64 * 1024)).foo;
-
-foo(0);
+foo();