Retain elements a finer granularity than library.

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

Index: dart/sdk/lib/_internal/compiler/implementation/compiler.dart
diff --git a/dart/sdk/lib/_internal/compiler/implementation/compiler.dart b/dart/sdk/lib/_internal/compiler/implementation/compiler.dart
index 1aa47b763707039c52ea28dda80d0bcf9c61a5b0..504ef854c29bd948236539a81b581165d8c009b4 100644
--- a/dart/sdk/lib/_internal/compiler/implementation/compiler.dart
+++ b/dart/sdk/lib/_internal/compiler/implementation/compiler.dart
@@ -331,6 +331,9 @@ abstract class Compiler implements DiagnosticListener {
    */
   final String globalJsName;
 
+  /// Emit terse diagnostics without howToFix.
+  final bool terseDiagnostics;
+
   final api.CompilerOutputProvider outputProvider;
 
   bool disableInlining = false;
@@ -387,6 +390,9 @@ abstract class Compiler implements DiagnosticListener {
   // Initialized when symbolImplementationClass has been resolved.
   FunctionElement symbolValidatedConstructor;
 
+  // Initialized when mirrorsUsedClass has been resolved.
+  FunctionElement mirrorsUsedConstructor;
+
   // Initialized when dart:mirrors is loaded.
   ClassElement deferredLibraryClass;
 
@@ -525,6 +531,7 @@ abstract class Compiler implements DiagnosticListener {
             this.sourceMapUri: null,
             this.buildId: UNDETERMINED_BUILD_ID,
             this.globalJsName: r'$',
+            this.terseDiagnostics: false,
             outputProvider,
             List<String> strips: const []})
       : this.analyzeOnly = analyzeOnly || analyzeSignaturesOnly,
@@ -746,6 +753,8 @@ abstract class Compiler implements DiagnosticListener {
     } else if (symbolImplementationClass == cls) {
       symbolValidatedConstructor = symbolImplementationClass.lookupConstructor(
           symbolValidatedConstructorSelector);
+    } else if (mirrorsUsedClass == cls) {
+      mirrorsUsedConstructor = cls.constructors.head;
     }
   }
 
@@ -801,7 +810,9 @@ abstract class Compiler implements DiagnosticListener {
           '$missingHelperClasses');
     }
 
-    types = new Types(this, dynamicClass);
+    if (types == null) {
+      types = new Types(this, dynamicClass);
+    }
     backend.initializeHelperClasses();
 
     dynamicClass.ensureResolved(this);
@@ -1171,7 +1182,7 @@ abstract class Compiler implements DiagnosticListener {
                    MessageKind errorCode,
                    [Map arguments = const {}]) {
     reportMessage(spanFromSpannable(node),
-                  errorCode.error(arguments),
+                  errorCode.error(arguments, terseDiagnostics),
                   api.Diagnostic.ERROR);
   }
 
@@ -1187,21 +1198,21 @@ abstract class Compiler implements DiagnosticListener {
   void reportWarningCode(Spannable node, MessageKind errorCode,
                          [Map arguments = const {}]) {
     reportMessage(spanFromSpannable(node),
-                  errorCode.error(arguments),
+                  errorCode.error(arguments, terseDiagnostics),
                   api.Diagnostic.WARNING);
   }
 
   void reportInfo(Spannable node, MessageKind errorCode,
                   [Map arguments = const {}]) {
     reportMessage(spanFromSpannable(node),
-                  errorCode.error(arguments),
+                  errorCode.error(arguments, terseDiagnostics),
                   api.Diagnostic.INFO);
   }
 
   void reportHint(Spannable node, MessageKind errorCode,
                   [Map arguments = const {}]) {
     reportMessage(spanFromSpannable(node),
-                  errorCode.error(arguments),
+                  errorCode.error(arguments, terseDiagnostics),
                   api.Diagnostic.HINT);
   }