Add mirrors_reader_test.

sdk/lib/_internal/compiler/implementation/compiler.dart

Index: sdk/lib/_internal/compiler/implementation/compiler.dart
diff --git a/sdk/lib/_internal/compiler/implementation/compiler.dart b/sdk/lib/_internal/compiler/implementation/compiler.dart
index d13da550c6b8a3809a3797be106b85ee7f9521e4..2551bf87be79a77f8ebbbffe9e80a602d417794a 100644
--- a/sdk/lib/_internal/compiler/implementation/compiler.dart
+++ b/sdk/lib/_internal/compiler/implementation/compiler.dart
@@ -499,10 +499,7 @@ abstract class Compiler implements DiagnosticListener {
       return f();
     } on SpannableAssertionFailure catch (ex) {
       if (!hasCrashed) {
-        String message = (ex.message != null) ? tryToString(ex.message)
-                                              : tryToString(ex);
-        SourceSpan span = spanFromSpannable(ex.node);
-        reportError(ex.node, MessageKind.GENERIC, {'text': message});
+        reportAssertionFailure(ex);
         pleaseReportCrash();
       }
       hasCrashed = true;
@@ -1397,6 +1394,13 @@ abstract class Compiler implements DiagnosticListener {
 
   void reportDiagnostic(SourceSpan span, String message, api.Diagnostic kind);
 
+  void reportAssertionFailure(SpannableAssertionFailure ex) {
+    String message = (ex.message != null) ? tryToString(ex.message)
+                                          : tryToString(ex);
+    SourceSpan span = spanFromSpannable(ex.node);
+    reportError(ex.node, MessageKind.GENERIC, {'text': message});
+  }
+
   SourceSpan spanFromTokens(Token begin, Token end, [Uri uri]) {
     if (begin == null || end == null) {
       // TODO(ahe): We can almost always do better. Often it is only