Fix for problem from Felix Meschberger:

When handling an Exception the Context tries to get the current script
and line number from the Java Stacktrace. To get the indication of which
entry in the trace might be an ECMA script, the file extension ".js" is
assumed.

For our integration we use the standard extension ".ecma" which collides
with the above assumption. But we don't force this extension, we just
have a convention. We name these files ".ecma" as they are not plain
ECMA but JSP-like ECMA. That is instead of using Java as the programming
language we use ECMA. In this respect they would be ".esp".

js/rhino/src/org/mozilla/javascript/Context.java

@@ -1844,7 +1844,7 @@ public class Context {
                      open < colon && colon < close) 
             {
                 String fileStr = s.substring(open + 1, colon);
-                if (fileStr.endsWith(".js")) {
+                if (!fileStr.endsWith(".java")) {
                     String lineStr = s.substring(colon + 1, close);
                     try {
                         linep[0] = Integer.parseInt(lineStr);