easysync: add clear method to stringAssembler

Author: webzwo0i

src/static/js/Changeset.js

@@ -677,6 +677,7 @@ exports.stringAssembler = () => ({
    * @param {string} x -
    */
   append(x) { this._str += String(x); },
+  clear() { this._str = ''; },
   toString() { return this._str; },
 });
 

src/tests/frontend/specs/easysync-assembler.js

@@ -167,7 +167,7 @@ describe('easysync-assembler', function () {
     expect(assem.toString()).to.equal('*3*4*5|3+f*1*4*5|1+1*1*4*5+4');
   });
 
-  xit('smartOpAssembler clear should empty internal assemblers', async function () {
+  it('smartOpAssembler clear should empty internal assemblers', async function () {
     const x = '-c*3*4+6|3=az*asdf0*1*2*3+1=1-1+1*0+1=1-1+1|c=c-1';
     const iter = Changeset.opIterator(x);
     const assem = Changeset.smartOpAssembler();