Highlight line when targeted by link

This would change appearance of a code line when it is targeted by a
link hash (i.e. a link to a file ending with #<line-number>).

Change-Id: Iaa4d09efb42c34aead8ebdfcbe1c2f2a30787fe2

gitiles-servlet/src/main/resources/com/google/gitiles/static/base.css

diff --git a/gitiles-servlet/src/main/resources/com/google/gitiles/static/base.css b/gitiles-servlet/src/main/resources/com/google/gitiles/static/base.css
index c64b14d..a1cd902 100644
--- a/gitiles-servlet/src/main/resources/com/google/gitiles/static/base.css
+++ b/gitiles-servlet/src/main/resources/com/google/gitiles/static/base.css
@@ -459,6 +459,9 @@
   min-height: 1em;
   padding-left: 10px;
 }
+.FileContents-lineContents:target {
+  background: #cfd8dc;
+}
 .InlineReadme {
   border-top: 1px solid #ddd;
   margin: 10px 0;

gitiles-servlet/src/main/resources/com/google/gitiles/templates/ObjectDetail.soy

diff --git a/gitiles-servlet/src/main/resources/com/google/gitiles/templates/ObjectDetail.soy b/gitiles-servlet/src/main/resources/com/google/gitiles/templates/ObjectDetail.soy
index 70ad21f..a740370 100644
--- a/gitiles-servlet/src/main/resources/com/google/gitiles/templates/ObjectDetail.soy
+++ b/gitiles-servlet/src/main/resources/com/google/gitiles/templates/ObjectDetail.soy
@@ -261,8 +261,7 @@
           <tr class="u-pre u-monospace FileContents-line">
             <td class="u-lineNum u-noSelect FileContents-lineNum"
                 data-line-number="{$n}" onclick="window.location.hash='#{$n}'"></td>
-            <td class="FileContents-lineContents">
-              <a name="{$n}"></a>
+            <td class="FileContents-lineContents" id="{$n}">
               {foreach $span in $line}
                 <span class="{$span.classes}">{$span.text}</span>
               {/foreach}