Fix 104493:

We have a tool that looks for a scary noop case of assigning an instance field
to itself. this usually comes from a constructor that assigns a argument to a
instance field with the same name and then later the argument changes name. we
ran our tool on all of our classes we have in our classpath here and found this
problem in your code.

rhino1_5R2/src/org/mozilla/javascript/regexp/NativeRegExp.java line 159 it has:
        this.flags = flags;

This seems to be a bad cut and paste from the CompilerState constructor on line
2155. or has some initialization that used to work been lost?

js/rhino/src/org/mozilla/javascript/regexp/NativeRegExp.java

@@ -158,7 +158,6 @@ public class NativeRegExp extends IdScriptable implements Function {
             dumpRegExp(state, ren);
         this.lastIndex = 0;
         this.parenCount = state.parenCount;
-        this.flags = flags;
 
         scope = getTopLevelScope(scope);
         setPrototype(getClassPrototype(scope, "RegExp"));