Fix library scan of loose files

editor/tools/plugins/com.google.dart.tools.core/src/com/google/dart/tools/core/analysis/LibraryScanTask.java

Index: editor/tools/plugins/com.google.dart.tools.core/src/com/google/dart/tools/core/analysis/LibraryScanTask.java
===================================================================
--- editor/tools/plugins/com.google.dart.tools.core/src/com/google/dart/tools/core/analysis/LibraryScanTask.java	(revision 9776)
+++ editor/tools/plugins/com.google.dart.tools.core/src/com/google/dart/tools/core/analysis/LibraryScanTask.java	(working copy)
@@ -30,7 +30,8 @@
  * Scan the specified folder and all subfolders for Dart libraries. Add any libraries and loose dart
  * files found to the {@link AnalysisServer}.
  */
-public class LibraryScanTask extends Task {
+class LibraryScanTask extends Task {
+
   private static final long SCAN_BYTE_THRESHOLD = 10 * 1000 * 1024; // 10 MB
   private static final long SCAN_TIME_THRESHOLD = 10 * 1000; // ten seconds
 
@@ -112,8 +113,10 @@
       looseFiles.removeAll(lib.getSourceFiles());
       for (File sourcedFile : lib.getSourceFiles()) {
         Library otherLib = context.getCachedLibrary(sourcedFile);
-        if (otherLib != null && !otherLib.hasDirectives()) {
-          server.discard(otherLib.getFile());
+        // If there is no information about the sourcedFile currently in the cache
+        // make the assumption that it is not a library file rather than doing more work
+        if (otherLib == null || !otherLib.hasDirectives()) {
+          server.discard(sourcedFile);
         }
       }
       iter.remove();