Fixes an issue where a dom-if that is toggled synchronously true-false-true could fail to sync properties invalidated while false, since the hidden state is only checked at async render timing, and the newly added dirty-check could means nothing happens if the hidden state has been changed back to its previous value at last render.
Since __syncHostProperties has its own fast-path if there is nothing to sync, it need not be gated on the hidden dirty-check in `_showHideChildren).
Fixes an issue where a
dom-ifthat is toggled synchronously true-false-true could fail to sync properties invalidated while false, since the hidden state is only checked at async render timing, and the newly added dirty-check could means nothing happens if the hidden state has been changed back to its previous value at last render.Since
__syncHostPropertieshas its own fast-path if there is nothing to sync, it need not be gated on the hidden dirty-check in `_showHideChildren).