Fixes for html report

This forces a regen of the summary when a file is recompiled.  It also suppresses dart: entries during normal compilation.

R=jmesserly@google.com

Review URL: https://codereview.chromium.org/1523353002 .

lib/src/report/html_reporter.dart

@@ -93,8 +93,10 @@ class HtmlReporter implements AnalysisErrorListener {
     keys = result.system.keys.toList()..sort();
     for (String name in keys) {
       LibrarySummary summary = result.system[name];
-      summaries.add(new SummaryInfo(
-          'Dart: code', name, 'dart:${name}', summary.messages));
+      if (summary.messages.isNotEmpty) {
+        summaries.add(new SummaryInfo(
+            'Dart: code', name, 'dart:${name}', summary.messages));
+      }
     }
 
     // Loose files

lib/src/server/dependency_graph.dart

@@ -32,6 +32,7 @@ import '../compiler.dart' show defaultRuntimeFiles;
 import '../info.dart';
 import '../options.dart';
 import '../report.dart';
+import '../report/html_reporter.dart';
 
 /// Holds references to all source nodes in the import graph. This is mainly
 /// used as a level of indirection to ensure that each source has a canonical
@@ -146,6 +147,8 @@ abstract class SourceNode {
     }
   }
 
+  void clearSummary() {}
+
   void saveUpdatedContents() {}
 
   String toString() {
@@ -183,14 +186,20 @@ class HtmlSourceNode extends SourceNode {
       : runtimeDeps = graph.runtimeDeps,
         super(graph, uri, source);
 
+  @override
+  void clearSummary() {
+    var reporter = graph._reporter;
+    if (reporter is HtmlReporter) {
+      reporter.reporter.clearHtml(uri);
+    } else if (reporter is SummaryReporter) {
+      reporter.clearHtml(uri);
+    }
+  }
+
   @override
   void update() {
     super.update();
     if (needsRebuild) {
-      var reporter = graph._reporter;
-      if (reporter is SummaryReporter) {
-        reporter.clearHtml(uri);
-      }
       document = html.parse(contents, generateSpans: true);
       var newScripts = new Set<DartSourceNode>();
       var tags = document.querySelectorAll('script[type="application/dart"]');
@@ -290,16 +299,21 @@ class DartSourceNode extends SourceNode {
     graph._context.setContents(_source, _source.contents.data);
   }
 
+  @override
+  void clearSummary() {
+    var reporter = graph._reporter;
+    if (reporter is HtmlReporter) {
+      reporter.reporter.clearLibrary(uri);
+    } else if (reporter is SummaryReporter) {
+      reporter.clearLibrary(uri);
+    }
+  }
+
   @override
   void update() {
     super.update();
 
     if (needsRebuild) {
-      var reporter = graph._reporter;
-      if (reporter is SummaryReporter) {
-        reporter.clearLibrary(uri);
-      }
-
       // If the defining compilation-unit changed, the structure might have
       // changed.
       var unit = parseDirectives(contents, name: _source.fullName);

lib/src/server/server.dart

@@ -89,6 +89,7 @@ class ServerCompiler extends AbstractCompiler {
   }
 
   bool _buildSource(SourceNode node) {
+    node.clearSummary();
     if (node is HtmlSourceNode) {
       _buildHtmlFile(node);
     } else if (node is DartSourceNode) {