### Eclipse Workspace Patch 1.0
#P org.eclipse.wst.jsdt.debug.core
Index: src/org/eclipse/wst/jsdt/debug/internal/core/launching/SourceLookup.java
===================================================================
RCS file: /cvsroot/webtools/org.eclipse.jsdt/plugins/org.eclipse.wst.jsdt.debug.core/src/org/eclipse/wst/jsdt/debug/internal/core/launching/SourceLookup.java,v
retrieving revision 1.10
diff -u -r1.10 SourceLookup.java
--- src/org/eclipse/wst/jsdt/debug/internal/core/launching/SourceLookup.java	6 Sep 2011 19:50:54 -0000	1.10
+++ src/org/eclipse/wst/jsdt/debug/internal/core/launching/SourceLookup.java	7 Oct 2011 18:02:39 -0000
@@ -54,7 +54,13 @@
 			return ((IJavaScriptStackFrame) object).getSourceName();
 		}
 		if(object instanceof IScript) {
-			return URIUtil.lastSegment(((IScript)object).sourceURI());
+			String name = URIUtil.lastSegment(((IScript)object).sourceURI());
+			if(!JavaScriptCore.isJavaScriptLikeFileName(name)) {
+				//append .js, there is no case where we would look up a file with no extension from a script node
+				StringBuffer buf = new StringBuffer(name.length()+3);
+				buf.append(name).append('.').append(Constants.JS_EXTENSION);
+				return buf.toString();
+			}
 		}
 		return null;
 	}