deps/v8/src/js/regexp.js
function RegExpGetIgnoreCase() {
  if (!IS_REGEXP(this)) {
    // TODO(littledan): Remove this RegExp compat workaround
    if (this === GlobalRegExpPrototype) {
      %IncrementUseCounter(kRegExpPrototypeOldFlagGetter);
      return UNDEFINED;
    }
    throw MakeTypeError(kRegExpNonRegExp, "RegExp.prototype.ignoreCase");
  }
  return TO_BOOLEAN(REGEXP_IGNORE_CASE(this));
}
function RegExpGetIgnoreCase() {
  if (!IS_REGEXP(this)) {
    // TODO(littledan): Remove this RegExp compat workaround
    if (this === GlobalRegExpPrototype) {
      %IncrementUseCounter(kRegExpPrototypeOldFlagGetter);
      return UNDEFINED;
    }
    throw MakeTypeError(kRegExpNonRegExp, "RegExp.prototype.ignoreCase");
  }
  return TO_BOOLEAN(REGEXP_IGNORE_CASE(this));
}
function RegExpGetIgnoreCase ( ) { if ( ! IS_REGEXP ( this ) ) { // TODO(littledan): Remove this RegExp compat workaround if ( this === GlobalRegExpPrototype ) { % IncrementUseCounter ( kRegExpPrototypeOldFlagGetter ) ; return UNDEFINED ; } throw MakeTypeError ( kRegExpNonRegExp , "RegExp.prototype.ignoreCase" ) ; } return TO_BOOLEAN ( REGEXP_IGNORE_CASE ( this ) ) ; }
ES6 21.2.5.5.
ES6 21 . 2 . 5 . 5 .