Bug 530018 - Add comment to explain why typedef is neceessary. (no r)

js/src/jsopcode.h

@@ -424,6 +424,13 @@ js_DecompileFunctionBody(JSPrinter *jp);
 extern JSBool
 js_DecompileFunction(JSPrinter *jp);
 
+/*
+ * Some C++ compilers treat the language linkage (extern "C" vs.
+ * extern "C++") as part of function (and thus pointer-to-function)
+ * types. The use of this typedef (defined in "C") ensures that
+ * js_DecompileToString's definition (in "C++") gets matched up with
+ * this declaration.
+ */
 typedef JSBool (* JSDecompilerPtr)(JSPrinter *);
 
 extern JSString *