build: fix runtime errors not being logged out on karma initialization (#74)

* Equivalent commit to angular/components#9888

Author: CaerusKaru

karma-test-shim.js

@@ -70,7 +70,13 @@ System.config({
 // Configure the Angular test bed and run all specs once configured.
 configureTestBed()
   .then(runSpecs)
-  .then(__karma__.start, __karma__.error);
+  .then(__karma__.start, function(error) {
+    // Passing in the error object directly to Karma won't log out the stack trace and
+    // passing the `originalErr` doesn't work correctly either. We have to log out the
+    // stack trace so we can actually debug errors before the tests have started.
+    console.error(error.originalErr.stack);
+    __karma__.error(error);
+  });
 
 
 /** Runs the specs in Karma. */