autocomplete: add support for displaying md-char-counter when md-input-maxlength is used

[ninety7]

In order to show the md-char-counter on the autocomplete input when using min/maxlength validators, we should switch from using ng-min/maxlength to their md-* counterparts. I see a very simple code change on the directive's templates.

What would need further discussion is how to update the md-char-counter after an item selection, as well as how will this impact the md-item-text attribute or vice-versa.

Angular Versions:

• Angular Version: 1.5.7
• Angular Material Version: 1.1.0

Additional Information:

• Browser Type: *
• Browser Version: *
• OS: *

[devversion]

I'm not sure I completely understand, why we should automatically transform the ng-min/maxlength attributes to a md- prefixed attribute?

General info about ng-min/maxlength on the autocomplete directive itself

• The reason why we use the md- prefix here, because when using the ng- prefix, the actual Angular Directive will try to find an associated input on the autocomplete.
  This means an error will be thrown.

[ninety7]

The main purpose for this is to show the md-char-counter on the autocomplete input when having max/min length validators.

[Splaktar]

I created a CodePen demo for investigating this. I also verified locally that a simple change to MdAutocomplete to change ng-maxlength="inputMaxlength" to md-maxlength="{{inputMaxlength}}" causes the autocomplete to show the md-char-counter.

[Splaktar]

[Splaktar]

I did the easy parts of this in https://github.com/DevIntent/material/commit/056e5ff2cc5f4527a3fa763bd0601d730f9c53d6, but as mentioned in the OP, the md-char-counter is not updated when a selection is made.