Warn about overriding operator== but not hashCode.

dart/sdk/lib/_internal/compiler/implementation/dart2js.dart

Index: dart/sdk/lib/_internal/compiler/implementation/dart2js.dart
diff --git a/dart/sdk/lib/_internal/compiler/implementation/dart2js.dart b/dart/sdk/lib/_internal/compiler/implementation/dart2js.dart
index ce1690b9b3ab8ad391658569235d701b047f11a4..635f8f0a45cb732ece397b03a4a12e47ce052899 100644
--- a/dart/sdk/lib/_internal/compiler/implementation/dart2js.dart
+++ b/dart/sdk/lib/_internal/compiler/implementation/dart2js.dart
@@ -227,6 +227,8 @@ void compile(List<String> argv) {
                       (_) => diagnosticHandler.throwOnError = true),
     new OptionHandler('--suppress-warnings',
                       (_) => diagnosticHandler.showWarnings = false),
+    new OptionHandler('--suppress-hints',
+                      (_) => diagnosticHandler.showHints = false),
     new OptionHandler('--output-type=dart|--output-type=js', setOutputType),
     new OptionHandler('--verbose', setVerbose),
     new OptionHandler('--version', (_) => wantVersion = true),
@@ -479,6 +481,9 @@ Supported options:
   --suppress-warnings
     Do not display any warnings.
 
+  --suppress-hints
+    Do not display any hints.
+
   --enable-diagnostic-colors
     Add colors to diagnostic messages.