Abstract methods with overloads get duplicated

[tbosch]

Given this:

abstract class Base {
  public abstract publicAbstract(): void;
  public abstract publicAbstract(arg: number): void;

Tsickle produces this:

abstract class Base {
/**
 * @abstract
 * @return {void}
 */
publicAbstract() {}
/**
  * @abstract
  * @param {number} arg
  * @return {void}
  */
publicAbstract(arg: number) {}
}

Related to #180

[tbosch]

No more a problem as tscikle now produces this JavaScript, which is correct:

/**
 * @abstract
 */
class Base {
}
function Base_tsickle_Closure_declarations() {
    /**
     * @abstract
     * @return {void}
     */
    Base.prototype.publicAbstract = function () { };
    /**
     * @abstract
     * @param {number} arg
     * @return {void}
     */
    Base.prototype.publicAbstract = function (arg) { };
}