[wasm] Forbid sign mismatch in asm typer.

test/mjsunit/wasm/asm-wasm-i32.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
 
 function WrapInAsmModule(func) {
   function MODULE_NAME(stdlib) {
     "use asm";
     var imul = stdlib.Math.imul;
@@ skipping 49 matching lines @@
 
 function i32_mul(a, b) {
   a = a | 0;
   b = b | 0;
   return imul(a, b) | 0;
 }
 
 function i32_div(a, b) {
   a = a | 0;
   b = b | 0;
-  return (a / b) | 0;
+  return ((a | 0) / (b | 0)) | 0;
 }
 
 function i32_mod(a, b) {
   a = a | 0;
   b = b | 0;
-  return (a % b) | 0;
+  return ((a | 0) % (b | 0)) | 0;
 }
 
 function i32_and(a, b) {
   a = a | 0;
   b = b | 0;
   return (a & b) | 0;
 }
 
 function i32_or(a, b) {
   a = a | 0;
@@ skipping 156 matching lines @@
         for (a of inputs) {
           for (b of inputs) {
             assertEquals(func(a, b), module.main(a, b));
           }
         }
       }
     });
   }
 
 })();