fix(inputs): ignoring input events in IE caused by placeholder changes o...

...r focus/blur on inputs with placeholders

This is my attempt at fixing #8242 as well as the extra placeholder issues with focus/blur. I'm assuming I'm missing a weird test case that still breaks somewhere, but I still think this is an improvement (it definitely is for my use cases).
same here, come to think of it. it should really just be `!!this.placeholder`