[wasm] Provide better stack traces for asm.js code

test/mjsunit/mjsunit.js

 // Copyright 2008 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 99 matching lines @@
 // Assert that the function code is (not) optimized.  If "no sync" is passed
 // as second argument, we do not wait for the concurrent optimization thread to
 // finish when polling for optimization status.
 // Only works with --allow-natives-syntax.
 var assertOptimized;
 var assertUnoptimized;
 
 // Assert that a string contains another expected substring.
 var assertContains;
 
+// Assert that a string matches a given regex.
+var assertMatches;
+
 
 (function () {  // Scope for utility functions.
 
   var ObjectPrototypeToString = Object.prototype.toString;
   var NumberPrototypeValueOf = Number.prototype.valueOf;
   var BooleanPrototypeValueOf = Boolean.prototype.valueOf;
   var StringPrototypeValueOf = String.prototype.valueOf;
   var DatePrototypeValueOf = Date.prototype.valueOf;
   var RegExpPrototypeToString = RegExp.prototype.toString;
   var ArrayPrototypeMap = Array.prototype.map;
@@ skipping 288 matching lines @@
     }
     throw new MjsUnitAssertionError(message);
   };
 
   assertContains = function(sub, value, name_opt) {
     if (value == null ? (sub != null) : value.indexOf(sub) == -1) {
       fail("contains '" + String(sub) + "'", value, name_opt);
     }
   };
 
+  assertMatches = function(regexp, str, name_opt) {
+    if (!(regexp instanceof RegExp)) {
+      regexp = new RegExp(regexp);
+    }
+    if (!str.match(regexp)) {
+      fail("should match '" + regexp + "'", str, name_opt);
+    }
+  };
+
   var OptimizationStatusImpl = undefined;
 
   var OptimizationStatus = function(fun, sync_opt) {
     if (OptimizationStatusImpl === undefined) {
       try {
         OptimizationStatusImpl = new Function(
             "fun", "sync", "return %GetOptimizationStatus(fun, sync);");
       } catch (e) {
         throw new Error("natives syntax not allowed");
       }
     }
     return OptimizationStatusImpl(fun, sync_opt);
   }
 
   assertUnoptimized = function assertUnoptimized(fun, sync_opt, name_opt) {
     if (sync_opt === undefined) sync_opt = "";
     assertTrue(OptimizationStatus(fun, sync_opt) !== 1, name_opt);
   }
 
   assertOptimized = function assertOptimized(fun, sync_opt, name_opt) {
     if (sync_opt === undefined) sync_opt = "";
     assertTrue(OptimizationStatus(fun, sync_opt) !== 2, name_opt);
   }
 
 })();