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

test/mjsunit/mjsunit.js

Index: test/mjsunit/mjsunit.js
diff --git a/test/mjsunit/mjsunit.js b/test/mjsunit/mjsunit.js
index 6a7c2da9e47d1ca56b52c98b3afbd2a2b6d72b6c..86052ee0a108fb377ad97f4cde220d26afe82bb2 100644
--- a/test/mjsunit/mjsunit.js
+++ b/test/mjsunit/mjsunit.js
@@ -117,6 +117,9 @@ 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.
 
@@ -425,6 +428,15 @@ var assertContains;
     }
   };
 
+  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) {