One more fix for making removing overlays incremental 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 70871f9bbb7ebdc55fa428cf9db3bad75577d9f4..095c2938dc4489ac630e17ad90f1a7f48849d092 100644
--- a/pkg/analyzer/lib/src/context/context.dart
+++ b/pkg/analyzer/lib/src/context/context.dart
@@ -970,13 +970,12 @@ class AnalysisContextImpl implements InternalAnalysisContext {
       // contents is the same as it was in the overlay.
       try {
         TimestampedData<String> fileContents = getContents(source);
-        String fileContentsData = fileContents.data;
-        if (fileContentsData == originalContents) {
-          entry.setValue(CONTENT, fileContentsData, TargetedResult.EMPTY_LIST);
-          entry.modificationTime = fileContents.modificationTime;
+        newContents = fileContents.data;
+        entry.modificationTime = fileContents.modificationTime;
+        if (newContents == originalContents) {
+          entry.setValue(CONTENT, newContents, TargetedResult.EMPTY_LIST);
           changed = false;
         }
-        newContents = fileContentsData;
       } catch (e) {}
       // If not the same content (e.g. the file is being closed without save),
       // then force analysis.