no-unused-variable: variable used in decorator function throws error

[dms1lva]

Bug Report

• TSLint version: 3.13.0
• TypeScript version: 1.8.10
• Running TSLint via: CLI

TypeScript code being linted

class NiceClass {
  @myNiceDecorator()
  public methodWithDecorator() {

  }

  private methodUsedInDecorator() {

  }
}

function myNiceDecorator() {
  this.methodUsedInDecorator();
}

with tslint.json configuration:

{
     "rules" :{
         "no-unused-variable": true
     }
}

Actual behavior

This error is thrown:
random.ts[7, 11]: Unused method: 'methodUsedInDecorator'

Expected behavior

No error should be thrown

[andy-hanson]

Should be fixed by #2235.