Add example and tests for +input-placeholder.

doc-src/content/examples/compass/css3/input-placeholder.haml

@@ -0,0 +1,8 @@
+---
+title: Input Placeholder
+description: css3 mixin to style input placeholders
+framework: compass
+stylesheet: compass/css3/_user-interface.scss
+example: true
+---
+= render "partials/example"

doc-src/content/examples/compass/css3/input-placeholder/markup.haml

@@ -0,0 +1,3 @@
+%form{:action => "", :method => "get"}
+  %label{:for => "input"} Input
+  %input{:type => "text", :name => "input" :placeholder => "Type something…"}

doc-src/content/examples/compass/css3/input-placeholder/stylesheet.sass

@@ -0,0 +1,8 @@
+@import compass/css3/user-interface
+
+input[type="text"] {
+	+input-placeholder {
+		color: #bfbfbf
+		font-style: italic
+	}
+}

test/fixtures/stylesheets/compass/sass/user-interface.scss

@@ -2,4 +2,11 @@
 
 .user-select {
   @include user-select(none);
+}
+
+.input-placeholder {
+	@include input-placeholder {
+		color: #bfbfbf;
+		font-style: italic;
+	}
 }