shouldBecome* outputs variable name instead of its value on failure

LayoutTests/resources/js-test.js

 // svg/dynamic-updates tests set enablePixelTesting=true, as we want to dump text + pixel results
 if (self.testRunner) {
     if (self.enablePixelTesting)
         testRunner.dumpAsTextWithPixelResults();
     else
         testRunner.dumpAsText();
 }
 
 var description, debug, successfullyParsed, errorMessage;
 
@@ skipping 211 matching lines @@
 }
 
 function shouldBecomeEqual(_a, _b, completionHandler, timeout)
 {
   if (typeof _a != "string" || typeof _b != "string")
     debug("WARN: shouldBecomeEqual() expects string arguments");
 
   if (timeout === undefined)
     timeout = 500;
 
+  var _bv;
   var condition = function() {
     var exception;
     var _av;
     try {
       _av = eval(_a);
     } catch (e) {
       exception = e;
     }
-    var _bv = eval(_b);
+    _bv = eval(_b);
     if (exception)
       testFailed(_a + " should become " + _bv + ". Threw exception " + exception);
     if (isResultCorrect(_av, _bv)) {
       testPassed(_a + " became " + _b);
       return true;
     }
     return false;
   };
   var failureTime = Date.now() + timeout;
   var failureHandler = function () {
-    testFailed(_a + " failed to change to " + _b + " in " + (timeout / 1000) + " seconds.");
+    testFailed(_a + " failed to change to " + _bv + " in " + (timeout / 1000) + " seconds.");
     completionHandler();
   };
   _waitForCondition(condition, failureTime, completionHandler, failureHandler);
 }
 
 function shouldBecomeEqualToString(value, reference, completionHandler, timeout)
 {
   if (typeof value !== "string" || typeof reference !== "string")
     debug("WARN: shouldBecomeEqualToString() expects string arguments");
   var unevaledString = JSON.stringify(reference);
@@ skipping 79 matching lines @@
     testFailed(_a + " should not be " + _bv + ".");
 }
 
 function shouldBecomeDifferent(_a, _b, completionHandler, timeout)
 {
   if (typeof _a != "string" || typeof _b != "string")
     debug("WARN: shouldBecomeDifferent() expects string arguments");
   if (timeout === undefined)
     timeout = 500;
 
+  var _bv;
   var condition = function() {
     var exception;
     var _av;
     try {
       _av = eval(_a);
     } catch (e) {
       exception = e;
     }
-    var _bv = eval(_b);
+    _bv = eval(_b);
     if (exception)
       testFailed(_a + " should became not equal to " + _bv + ". Threw exception " + exception);
     if (!isResultCorrect(_av, _bv)) {
       testPassed(_a + " became different from " + _b);
       return true;
     }
     return false;
   };
   var failureTime = Date.now() + timeout;
   var failureHandler = function () {
-    testFailed(_a + " did not become different from " + _b + " in " + (timeout / 1000) + " seconds.");
+    testFailed(_a + " did not become different from " + _bv + " in " + (timeout / 1000) + " seconds.");
     completionHandler();
   };
   _waitForCondition(condition, failureTime, completionHandler, failureHandler);
 }
 
 function shouldBeTrue(_a) { shouldBe(_a, "true"); }
 function shouldBeTrueQuiet(_a) { shouldBe(_a, "true", true); }
 function shouldBeFalse(_a) { shouldBe(_a, "false"); }
 function shouldBeNaN(_a) { shouldBe(_a, "NaN"); }
 function shouldBeNull(_a) { shouldBe(_a, "null"); }
@@ skipping 304 matching lines @@
     testPassed = function(msg) {
         workerPort.postMessage('PASS:' + msg);
     }
     finishJSTest = function() {
         workerPort.postMessage('DONE:');
     }
     debug = function(msg) {
         workerPort.postMessage(msg);
     }
 }