Revert "Remove workaround regarding newlines on GWT UI"

This reverts commit 8dfc226edafd259f089755e47cdf4bd3c1a82f86.

It seems to cause an off-by-one error in line highlighting under
some circumstances. The highlighting is shown on the line after
the line that was actually changed.

Bug: Issue 12646
Change-Id: I8385e9f7306af5e1b38fd726b3763fd7fe845aac

gerrit-gwtui/src/main/java/com/google/gerrit/client/diff/DiffInfo.java

diff --git a/gerrit-gwtui/src/main/java/com/google/gerrit/client/diff/DiffInfo.java b/gerrit-gwtui/src/main/java/com/google/gerrit/client/diff/DiffInfo.java
index d942c2e..cf40762 100644
--- a/gerrit-gwtui/src/main/java/com/google/gerrit/client/diff/DiffInfo.java
+++ b/gerrit-gwtui/src/main/java/com/google/gerrit/client/diff/DiffInfo.java
@@ -137,10 +137,7 @@
 
   private static void append(StringBuilder s, JsArrayString lines) {
     for (int i = 0; i < lines.length(); i++) {
-      if (s.length() > 0) {
-        s.append('\n');
-      }
-      s.append(lines.get(i));
+      s.append(lines.get(i)).append('\n');
     }
   }