Input Placeholder Compass Mixin

_placehoder.scss

@mixin placeholder() {
	&::-webkit-input-placeholder {
	    @content;
	}

	&:-moz-placeholder {
	    @content;
	}

	&::-moz-placeholder {
	    @content;
	}

	&:-ms-input-placeholder {
	    @content;
	}
}