Don't remove ResultData(s) for incrementally updated results.

pkg/analyzer/lib/src/context/context.dart

 // Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library analyzer.src.context.context;
 
 import 'dart:async';
 import 'dart:collection';
 
 import 'package:analyzer/instrumentation/instrumentation.dart';
@@ skipping 1709 matching lines @@
         }
       } catch (e) {}
     }
     // We need to invalidate the cache.
     {
       Object delta = null;
       if (AnalysisEngine.instance.limitInvalidationInTaskModel &&
           AnalysisEngine.isDartFileName(source.fullName)) {
         // TODO(scheglov) Incorrect implementation in general.
         entry.setState(TOKEN_STREAM, CacheState.FLUSHED);
-        entry.setState(SCAN_ERRORS, CacheState.FLUSHED);
         entry.setState(PARSED_UNIT, CacheState.FLUSHED);
-        entry.setState(PARSE_ERRORS, CacheState.FLUSHED);
-        CompilationUnit oldUnit = getResolvedCompilationUnit2(source, source);
-        if (oldUnit != null) {
-          CompilationUnit newUnit = parseCompilationUnit(source);
-          IncrementalCompilationUnitElementBuilder builder =
-              new IncrementalCompilationUnitElementBuilder(oldUnit, newUnit);
-          builder.build();
-          CompilationUnitElementDelta unitDelta = builder.unitDelta;
-          DartDelta dartDelta = new DartDelta(source);
-          dartDelta.hasDirectiveChange = unitDelta.hasDirectiveChange;
-          unitDelta.addedDeclarations.forEach(dartDelta.elementAdded);
-          unitDelta.removedDeclarations.forEach(dartDelta.elementRemoved);
-          delta = dartDelta;
+        List<Source> librarySources = getLibrariesContaining(source);
+        if (librarySources.length == 1) {
+          Source librarySource = librarySources[0];
+          CompilationUnit oldUnit =
+              getResolvedCompilationUnit2(source, librarySource);
+          if (oldUnit != null) {
+            CompilationUnit newUnit = parseCompilationUnit(source);
+            IncrementalCompilationUnitElementBuilder builder =
+                new IncrementalCompilationUnitElementBuilder(oldUnit, newUnit);
+            builder.build();
+            CompilationUnitElementDelta unitDelta = builder.unitDelta;
+            if (!unitDelta.hasDirectiveChange) {
+              DartDelta dartDelta = new DartDelta(source);
+              dartDelta.hasDirectiveChange = unitDelta.hasDirectiveChange;
+              unitDelta.addedDeclarations.forEach(dartDelta.elementAdded);
+              unitDelta.removedDeclarations.forEach(dartDelta.elementRemoved);
+              print(

[Brian Wilkerson, 2015/06/26 16:12:07]

Remove or comment out debugging statement?

+                  'dartDelta: add=${dartDelta.addedNames} remove=${dartDelta.removedNames}');
+              delta = dartDelta;
+              entry.setState(CONTENT, CacheState.INVALID, delta: delta);
+              return;
+            }
+          }
         }
       }
-      entry.setState(CONTENT, CacheState.INVALID, delta: delta);
+      entry.setState(CONTENT, CacheState.INVALID);
     }
     dartWorkManager.applyChange(
         Source.EMPTY_LIST, <Source>[source], Source.EMPTY_LIST);
     htmlWorkManager.applyChange(
         Source.EMPTY_LIST, <Source>[source], Source.EMPTY_LIST);
   }
 
   /**
    * Record that the give [source] has been deleted.
    */
@@ skipping 285 matching lines @@
         new PendingFuture<T>(_context, target, computeValue);
     if (!pendingFuture.evaluate(entry)) {
       _context._pendingFutureTargets
           .putIfAbsent(target, () => <PendingFuture>[])
           .add(pendingFuture);
       scheduleComputation();
     }
     return pendingFuture.future;
   }
 }