perf($parse): don't use reflective calls in generated functions

Chrome and FF are smart enough to notice that the key is is a string literal, so this change doesn't
make a difference there. Safari gets a boost. I haven't tested IE, but it can't cause harm there. :)

http://jsperf.com/fn-dereferencing

src/ng/parse.js

@@ -1020,7 +1020,7 @@ function getterFn(path, options, fullExp) {
                       // we simply dereference 's' on any .dot notation
                       ? 's'
                       // but if we are first then we check locals first, and if so read it first
-                      : '((k&&k.hasOwnProperty("' + key + '"))?k:s)') + '["' + key + '"]' + ';\n' +
+                      : '((k&&k.hasOwnProperty("' + key + '"))?k:s)') + '.' + key + ';\n' +
               (options.unwrapPromises
                 ? 'if (s && s.then) {\n' +
                   ' pw("' + fullExp.replace(/(["\r\n])/g, '\\$1') + '");\n' +