Remove JavaSystem from java_core.

pkg/analyzer/lib/src/generated/source.dart

Index: pkg/analyzer/lib/src/generated/source.dart
diff --git a/pkg/analyzer/lib/src/generated/source.dart b/pkg/analyzer/lib/src/generated/source.dart
index 41f6c8846edcb885d3cb4f8ee861b5ce60e31102..2fc6c2d161312632c7dcf305fb089110c7bbff54 100644
--- a/pkg/analyzer/lib/src/generated/source.dart
+++ b/pkg/analyzer/lib/src/generated/source.dart
@@ -42,6 +42,8 @@ class ContentCache {
    */
   HashMap<String, int> _stampMap = new HashMap<String, int>();
 
+  int _nextStamp = 0;
+
   /**
    * Visit all entries of this cache.
    */
@@ -82,7 +84,7 @@ class ContentCache {
       _stampMap.remove(fullName);
       return _contentMap.remove(fullName);
     } else {
-      int newStamp = JavaSystem.currentTimeMillis();
+      int newStamp = _nextStamp++;
       int oldStamp = _stampMap[fullName];
       _stampMap[fullName] = newStamp;
       // Occasionally, if this method is called in rapid succession, the