Remove unused `addDraftAtLine()`

Release-Notes: skip
Change-Id: I37f06df0e8961e761981117836cf6ec0517ecb70
diff --git a/polygerrit-ui/app/elements/diff/gr-diff-host/gr-diff-host.ts b/polygerrit-ui/app/elements/diff/gr-diff-host/gr-diff-host.ts
index c626d42d..f393025 100644
--- a/polygerrit-ui/app/elements/diff/gr-diff-host/gr-diff-host.ts
+++ b/polygerrit-ui/app/elements/diff/gr-diff-host/gr-diff-host.ts
@@ -908,11 +908,6 @@
     );
   }
 
-  addDraftAtLine(el: Element) {
-    assertIsDefined(this.diffElement);
-    this.diffElement.addDraftAtLine(el);
-  }
-
   clearDiffContent() {
     this.diffElement?.clearDiffContent();
   }
diff --git a/polygerrit-ui/app/elements/diff/gr-diff-host/gr-diff-host_test.ts b/polygerrit-ui/app/elements/diff/gr-diff-host/gr-diff-host_test.ts
index 9c0dea3..0abcaf5 100644
--- a/polygerrit-ui/app/elements/diff/gr-diff-host/gr-diff-host_test.ts
+++ b/polygerrit-ui/app/elements/diff/gr-diff-host/gr-diff-host_test.ts
@@ -709,16 +709,6 @@
     assert.deepEqual(element.getThreadEls(), [threadEl]);
   });
 
-  test('delegates addDraftAtLine(el)', () => {
-    const param0 = document.createElement('b');
-    assertIsDefined(element.diffElement);
-    const stub = sinon.stub(element.diffElement, 'addDraftAtLine');
-    element.addDraftAtLine(param0);
-    assert.isTrue(stub.calledOnce);
-    assert.equal(stub.lastCall.args.length, 1);
-    assert.equal(stub.lastCall.args[0], param0);
-  });
-
   test('delegates clearDiffContent()', () => {
     assertIsDefined(element.diffElement);
     const stub = sinon.stub(element.diffElement, 'clearDiffContent');