more care around generated names, fixes #60 #82 and #97

test/codegen/expect/methods.js

Index: test/codegen/expect/methods.js
diff --git a/test/codegen/expect/methods.js b/test/codegen/expect/methods.js
index ea96ac0df6e3de04c1b2952e3e4a07c829e5cc68..3fe7d7e5f013686666dfca83f1e2251e91523a0f 100644
--- a/test/codegen/expect/methods.js
+++ b/test/codegen/expect/methods.js
@@ -22,12 +22,12 @@ var methods;
         b = 0;
       return b;
     }
-    w(a, opt$) {
-      let b = opt$ && 'b' in opt$ ? opt$.b : null;
+    w(a, opts) {
+      let b = opts && 'b' in opts ? opts.b : null;
       return dart.notNull(a) + dart.notNull(b);
     }
-    ww(a, opt$) {
-      let b = opt$ && 'b' in opt$ ? opt$.b : 0;
+    ww(a, opts) {
+      let b = opts && 'b' in opts ? opts.b : 0;
       return dart.notNull(a) + dart.notNull(b);
     }
     get a() {