Pass operand to extension script JSR/JSL handlers

Sort of silly to have every handler immediately pull the operand out
of the file data.  (This is arguably less efficient, since we now
have to serialize the argument across the AppDomain boundary, but
we should be okay spending a few extra nanoseconds here.)

SourceGen/Examples/Scripts/InlineL1String.cs

@@ -49,10 +49,9 @@ namespace ExtensionScriptSample {
             return beforeLabel == CALL_LABEL || afterLabel == CALL_LABEL;
         }
 
-        public void CheckJsr(int offset, out bool noContinue) {
+        public void CheckJsr(int offset, int operand, out bool noContinue) {
             noContinue = false;
-            int target = Util.GetWord(mFileData, offset + 1, 2, false);
-            if (target != mInlineL1StringAddr) {
+            if (operand != mInlineL1StringAddr) {
                 return;
             }
             if (offset + 3 >= mFileData.Length) {