diff --git a/pkg/analyzer/lib/src/context/cache.dart b/pkg/analyzer/lib/src/context/cache.dart
index 104d89a..58dda21 100644
--- a/pkg/analyzer/lib/src/context/cache.dart
+++ b/pkg/analyzer/lib/src/context/cache.dart
@@ -617,6 +617,9 @@
     if (delta == null) {
       return false;
     }
+    if (!delta.shouldGatherChanges) {
+      return true;
+    }
     for (int i = 0; i < 64; i++) {
       bool hasVisitChanges = false;
       _visitResults(nextVisitId++, result,
@@ -1255,6 +1258,21 @@
 
   Delta(this.source);
 
+  /**
+   * Return `true` if this delta needs cache walking to gather additional
+   * changes before it can be used to [validate].  In this case [gatherChanges]
+   * is invoked for every targeted result in transitive dependencies, and
+   * [gatherEnd] is invoked after cache walking is done.
+   */
+  bool get shouldGatherChanges => false;
+
+  /**
+   * This method is called during a cache walk, so that the delta can gather
+   * additional changes to which are caused by the changes it already knows
+   * about.  Return `true` if a new change was added, so that one more cache
+   * walk will be performed (to include changes that depend on results which we
+   * decided to be changed later in the previous cache walk).
+   */
   bool gatherChanges(InternalAnalysisContext context, AnalysisTarget target,
       ResultDescriptor descriptor, Object value) {
     return false;
diff --git a/pkg/analyzer/lib/src/generated/incremental_resolver.dart b/pkg/analyzer/lib/src/generated/incremental_resolver.dart
index 9e2a1d4..c1bc461 100644
--- a/pkg/analyzer/lib/src/generated/incremental_resolver.dart
+++ b/pkg/analyzer/lib/src/generated/incremental_resolver.dart
@@ -77,6 +77,7 @@
     bool isByTask(TaskDescriptor taskDescriptor) {
       return taskDescriptor.results.contains(descriptor);
     }
+
     if (descriptor == CONTENT) {
       return DeltaResult.KEEP_CONTINUE;
     }
@@ -809,6 +810,7 @@
             }
           }
         }
+
         Element parentElement = ElementLocator.locate(newComment.parent);
         if (parentElement is ElementImpl) {
           setElementDocumentationComment(parentElement, parent);
diff --git a/pkg/analyzer/lib/src/task/dart.dart b/pkg/analyzer/lib/src/task/dart.dart
index da8fcec..04c4ec4 100644
--- a/pkg/analyzer/lib/src/task/dart.dart
+++ b/pkg/analyzer/lib/src/task/dart.dart
@@ -975,7 +975,7 @@
 final ListResultDescriptor<AnalysisError>
     STATIC_VARIABLE_RESOLUTION_ERRORS_IN_UNIT =
     new ListResultDescriptor<AnalysisError>(
-        'STATIC_VARIABLE_RESOLUTION_ERRORS_IN_UNIT', null);
+        'STATIC_VARIABLE_RESOLUTION_ERRORS_IN_UNIT', AnalysisError.NO_ERRORS);
 
 /**
  * The additional strong mode errors produced while verifying a
@@ -2563,6 +2563,9 @@
 
   DartDelta(Source source) : super(source);
 
+  @override
+  bool get shouldGatherChanges => true;
+
   /**
    * Add names that are changed in the given [references].
    * Return `true` if any change was added.
diff --git a/pkg/analyzer/test/src/context/cache_test.dart b/pkg/analyzer/test/src/context/cache_test.dart
index 1d4bc4f..387eae9 100644
--- a/pkg/analyzer/test/src/context/cache_test.dart
+++ b/pkg/analyzer/test/src/context/cache_test.dart
@@ -1244,6 +1244,9 @@
   _KeepContinueDelta(this.source, this.keepDescriptor);
 
   @override
+  bool get shouldGatherChanges => false;
+
+  @override
   bool gatherChanges(InternalAnalysisContext context, AnalysisTarget target,
       ResultDescriptor descriptor, Object value) {
     return false;