refactor($parse): Create idents lazily

Create the ident functions lazily as these are not used for filters not object literal properties
The generated functions that are not used can cause issues with some browsers

Closes #9131

Note: This may have cause some performance improvements
Could this line change to
```
primary = CONSTANTS[token.text] || getterFn(token.text, this.options, this.text);
```
...and avoid the `lazyFn` + `fn` setup above?