Bug fix for http://code.google.com/p/dart/issues/detail?id=347.

editor/tools/plugins/com.google.dart.tools.core/src/com/google/dart/tools/core/generator/FileGenerator.java

Index: editor/tools/plugins/com.google.dart.tools.core/src/com/google/dart/tools/core/generator/FileGenerator.java
===================================================================
--- editor/tools/plugins/com.google.dart.tools.core/src/com/google/dart/tools/core/generator/FileGenerator.java	(revision 1212)
+++ editor/tools/plugins/com.google.dart.tools.core/src/com/google/dart/tools/core/generator/FileGenerator.java	(working copy)
@@ -110,8 +110,6 @@
       // this is the check to see if the fileLocation is pointing to the location of the selected library, as mentioned above
       if (directoryOfLibrary != null && directoryOfLibrary.equals(fileLocation)) {
         // do nothing, current library is correct.
-        // Sanity Check
-        Assert.isTrue(library.getDefiningCompilationUnit().definesLibrary());
       } else {
         library = null;
       }