Tax Rate Search: First whack.

This is by no means complete.  A number of things need to be relocated
and optimized still, but it does a rough search, purely in JS, and
highlights the results in yellow.

includes/admin/settings/views/html-settings-tax.php

@@ -5,6 +5,44 @@ if ( ! defined( 'ABSPATH' ) ) {
 ?>
 <h3><?php printf( __( 'Tax Rates for the "%s" Class', 'woocommerce' ), $current_class ? esc_html( $current_class ) : __( 'Standard', 'woocommerce' ) ); ?></h3>
 <p><?php printf( __( 'Define tax rates for countries and states below. <a href="%s">See here</a> for available alpha-2 country codes.', 'woocommerce' ), 'http://en.wikipedia.org/wiki/ISO_3166-1#Current_codes' ); ?></p>
+
+<input type="search" class="tax-search" placeholder="<?php esc_attr_e( 'Search…', 'woocommerce' ); ?>" />
+<p class="num-results-found"></p>
+
+<script>
+	(function($){
+		function processTaxRateSearch() {
+			var searchText = this.value.toLowerCase(),
+				$table     = $('table.wc_tax_rates'),
+				$rows      = $table.find('tbody tr' ),
+				results    = 0;
+
+			if ( 0 === searchText.length ) {
+				$rows.removeClass('search-result-match');
+				$('.num-results-found' ).text('');
+				return;
+			}
+			$rows.each(function(){
+				var rowText = $(this).find(':input').map( function(){ return this.value; } ).get().join(' ');
+				if ( -1 !== rowText.toLowerCase().indexOf( searchText.toLowerCase() ) ) {
+					$(this).toggleClass( 'search-result-match', true );
+					results++;
+				} else {
+					$(this).toggleClass( 'search-result-match', false );
+				}
+			});
+			$('.num-results-found').text( ('<?php echo esc_js( __( '%d results found.', 'woocommerce' ) ); ?>').replace( '%d', results ) );
+
+		}
+		$('.tax-search' ).on( 'keyup search', processTaxRateSearch );
+	})(jQuery);
+</script>
+<style>
+	tr.search-result-match input {
+		background-color: yellow !important;
+	}
+</style>
+
 <table class="wc_tax_rates wc_input_table sortable widefat">
 	<thead>
 		<tr>