Reset AnalysisDriver after changes.

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

Index: pkg/analyzer/lib/src/context/context.dart
diff --git a/pkg/analyzer/lib/src/context/context.dart b/pkg/analyzer/lib/src/context/context.dart
index b2b22cf9673274e91bc3274c5f3d816b3ff04ae0..75335b6ec4ebf18b55ca725cf0aceade12a24ae3 100644
--- a/pkg/analyzer/lib/src/context/context.dart
+++ b/pkg/analyzer/lib/src/context/context.dart
@@ -1731,6 +1731,7 @@ class AnalysisContextImpl implements InternalAnalysisContext {
    * that referenced the source before it existed.
    */
   void _sourceAvailable(Source source) {
+    driver.reset();
     // TODO(brianwilkerson) This method needs to check whether the source was
     // previously being implicitly analyzed. If so, the cache entry needs to be
     // update to reflect the new status and an event needs to be generated to
@@ -1807,6 +1808,7 @@ class AnalysisContextImpl implements InternalAnalysisContext {
       }
       entry.setState(CONTENT, CacheState.INVALID);
     }
+    driver.reset();
     for (WorkManager workManager in workManagers) {
       workManager.applyChange(
           Source.EMPTY_LIST, <Source>[source], Source.EMPTY_LIST);
@@ -1848,6 +1850,7 @@ class AnalysisContextImpl implements InternalAnalysisContext {
    * Record that the given [source] has been removed.
    */
   void _sourceRemoved(Source source) {
+    driver.reset();
     _removeFromCache(source);
     _removeFromPriorityOrder(source);
   }