Revert "Implement override checks."

lib/compiler/implementation/dart2js.dart

Index: lib/compiler/implementation/dart2js.dart
diff --git a/lib/compiler/implementation/dart2js.dart b/lib/compiler/implementation/dart2js.dart
index 7c147ffeac761571f1d965bdcc4082ae247ba4fa..a4ce8c0ad021f619be40926d78c1adb932a2968a 100644
--- a/lib/compiler/implementation/dart2js.dart
+++ b/lib/compiler/implementation/dart2js.dart
@@ -194,7 +194,8 @@ void compile(List<String> argv) {
     isAborting = kind === api.Diagnostic.CRASH;
     bool fatal = (kind.ordinal & FATAL) != 0;
     bool isInfo = (kind.ordinal & INFO) != 0;
-    if (isInfo && uri === null && kind !== api.Diagnostic.INFO) {
+    if (isInfo) {
+      assert(uri === null);
       info(message, kind);
       return;
     }
@@ -209,8 +210,6 @@ void compile(List<String> argv) {
       color = colors.magenta;
     } else if (kind === api.Diagnostic.CRASH) {
       color = colors.red;
-    } else if (kind === api.Diagnostic.INFO) {
-      color = colors.green;
     } else {
       throw 'Unknown kind: $kind (${kind.ordinal})';
     }