Fixes a bug in recursive unit invalidation.

Review by: bobv

git-svn-id: https://google-web-toolkit.googlecode.com/svn/trunk@7258 8db76d5a-ed1c-0410-87a9-c151d255dfc7

dev/core/src/com/google/gwt/dev/javac/CompilationUnitInvalidator.java

diff --git a/dev/core/src/com/google/gwt/dev/javac/CompilationUnitInvalidator.java b/dev/core/src/com/google/gwt/dev/javac/CompilationUnitInvalidator.java
index 0a8cb3a..a317d3b 100644
--- a/dev/core/src/com/google/gwt/dev/javac/CompilationUnitInvalidator.java
+++ b/dev/core/src/com/google/gwt/dev/javac/CompilationUnitInvalidator.java
@@ -79,7 +79,7 @@
         for (ContentId ref : unitToCheck.getDependencies()) {
           if (!currentlyValidRefs.contains(ref)) {
             it.remove();
-            currentlyValidRefs.remove(unitToCheck.getDisplayLocation());
+            currentlyValidRefs.remove(unitToCheck.getContentId());
             changed = true;
             continue iterating;
           }