Fill CacheEntry.modificationTime for implicit sources.

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 7f8d7daae82b5c8103ee4865f6fe1576d00a1d20..d1e91720ec6653eb333683d99898301f1bba7377 100644
--- a/pkg/analyzer/lib/src/context/context.dart
+++ b/pkg/analyzer/lib/src/context/context.dart
@@ -679,6 +679,9 @@ class AnalysisContextImpl implements InternalAnalysisContext {
     CacheEntry entry = _cache.get(target);
     if (entry == null) {
       entry = new CacheEntry(target);
+      if (target is Source) {
+        entry.modificationTime = getModificationStamp(target);

[Brian Wilkerson, 2015/05/22 18:58:52]

Unless we explicitly want to not have a modification time for non-Source
targets, this could be:

Source source = target.source;
if (source != null) {
  entry.modificationTime = getModificationStamp(source);
}

[scheglov, 2015/05/22 19:17:30]

We use "modificationTime" only "_validateCacheConsistency", and do this only for
sources.
So, it seems that modificationTime for non-sources would not be used, at least
currently.

+      }
       _cache.put(entry);
     }
     return entry;