[asm] Fix lots of invalid asm.js tests

test/mjsunit/asm/float32array-negative-offset.js

 // Copyright 2014 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.
 
 var stdlib = this;
 var buffer = new ArrayBuffer(64 * 1024);
 var foreign = {}
 
 
 var m = (function Module(stdlib, foreign, heap) {
   "use asm";
   var MEM32 = new stdlib.Float32Array(heap);
   function load(i) {
     i = i|0;
-    i = +MEM32[i >> 2];
-    return i;
+    return +MEM32[i >> 2];
   }
   function store(i, v) {
     i = i|0;
     v = +v;
     MEM32[i >> 2] = v;
   }
   function load8(i) {
     i = i|0;
-    i = +MEM32[i + 8 >> 2];
-    return i;
+    return +MEM32[i + 8 >> 2];
   }
   function store8(i, v) {
     i = i|0;
     v = +v;
     MEM32[i + 8 >> 2] = v;
   }
   return { load: load, store: store, load8: load8, store8: store8 };
 })(stdlib, foreign, buffer);
 
 assertEquals(NaN, m.load(-8));
 assertEquals(NaN, m.load8(-16));
 m.store(0, 42.0);
 assertEquals(42.0, m.load8(-8));
 m.store8(-8, 99.0);
 assertEquals(99.0, m.load(0));
 assertEquals(99.0, m.load8(-8));