parse type params on object methods/getters/setters

[easrng]

these fail to parse:

({
  get x<T>(){}
});
({
  x<T>(){}
});

needs something like this i think

      parsePropertyValue(prop, isPattern, isGenerator, isAsync, startPos, startLoc, refDestructuringErrors, containsEsc) {
        prop.typeParameters = this.tsTryParseTypeParameters(this.tsParseConstModifier);
        if (prop.typeParameters && this.type === tt.colon)
          { this.unexpected(); }
        super.parsePropertyValue(prop, isPattern, isGenerator, isAsync, startPos, startLoc, refDestructuringErrors, containsEsc)
      }