Revert addition of input placeholder rules

This commit reverts the following 5 commits:

49392e9
f9572a4
79e2c16
2691e7a
567af2e

The `:moz-placeholder` rule doesn't have the desired effect because any
subsequent rule with higher specificity will result in the Firefox bug
resurfacing. There is no way to ensure that Firefox doesn't change the
color of the placeholder text. Example: https://tinker.io/e34a2

The `:focus::webkit-input-placeholder` normalization is being removed
because the current Chrome / Safari on Lion OSX behaviour is allowed in
the spec, Firefox is set to implement the same behaviour, and other
browsers may follow suit for usability reasons.

Some browser differences like these - low importance and in flux - can
be allowed to evolve and settle before assessing whether or not they
need or merit normalization.

normalize.css

@@ -1,4 +1,4 @@
-/*! normalize.css 2012-03-09T22:11 UTC - http://github.com/necolas/normalize.css */
+/*! normalize.css 2012-03-11T12:53 UTC - http://github.com/necolas/normalize.css */
 
 /* =============================================================================
    HTML5 display definitions
@@ -489,22 +489,6 @@ textarea {
     vertical-align: top; /* 2 */
 }
 
-/*
- * Addresses placeholder color unset in Firefox
- */
-
-:-moz-placeholder {
-    color: #a9a9a9;
-}
-
-/*
- * Addresses placeholder text remaining visible on focus in Chrome
- */
-
-:focus::-webkit-input-placeholder {
-    color: transparent;
-}
-
 
 /* =============================================================================
    Tables