Remove scrollbar from Commit Message

Now that the commit message must be explicitly selected
for display in the PatchScreen header, it makes sense to
assume that they want to see the whole thing and are
willing to vertical sacrifice some screen real estate to
do that.

Change-Id: I51466bbb90666f5b74d3b007b89d4cae7205330e

gerrit-gwtui/src/main/java/com/google/gerrit/client/patches/PatchScreen.java

@@ -259,7 +259,7 @@ public abstract class PatchScreen extends Screen implements
 
     historyTable = new HistoryTable(this);
 
-    commitMessageBlock = new CommitMessageBlock("6em");
+    commitMessageBlock = new CommitMessageBlock();
 
     topPanel = new FlowPanel();
     add(topPanel);