use $ as the operation rename for reserved word.

[qiaozha]

If we have an operation name delete, currently, we will rename it as deleteOperation because of the reserved word.
But we should rename it as $delete instead. see comment #2080 (comment)

[qiaozha]

function deleteOperation() {} // only exists in api layer
function $delete() {}

class A {
function delete() {} // we need to keep this, we should not normalize the name here.
}