Don't update incrementally invalid results.

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

Index: pkg/analyzer/lib/src/context/cache.dart
diff --git a/pkg/analyzer/lib/src/context/cache.dart b/pkg/analyzer/lib/src/context/cache.dart
index a6094216f7205e4d34128077c4502b53c45a28c6..163da9a84507499edc41aec1920b3a439ba98caa 100644
--- a/pkg/analyzer/lib/src/context/cache.dart
+++ b/pkg/analyzer/lib/src/context/cache.dart
@@ -509,14 +509,16 @@ class CacheEntry {
   }
 
   /**
-   * Set the value of the result represented by the given [descriptor] to the
-   * given [value], keep its dependency, invalidate all the dependent result.
+   * If the result represented by the given [descriptor] is valid, set
+   * it to the given [value], keep its dependency, and if [invalidateDependent]
+   * invalidate all the dependent result.
    */
   void setValueIncremental(
       ResultDescriptor descriptor, dynamic value, bool invalidateDependent) {
     ResultData data = getResultData(descriptor);
-    data.state = CacheState.VALID;
-    data.value = value;
+    if (data.state == CacheState.VALID) {

[Brian Wilkerson, 2015/11/20 19:47:47]

I think we want to also set the value if the state is FLUSHED.

+      data.value = value;
+    }
     if (invalidateDependent) {
       _invalidateDependentResults(nextInvalidateId++, data, null, 0);
     }