Set viewportMargin to Infinity on CodeMirror initialization

Because CodeMirror doesn't render lines until scrolled into view,
line widgets that are also manually added to diffTable will not be
put in the right spot. Fixed by setting viewportMargin to Infinity
on initialization and resetting to default later.

Fixed minor styling issues with CommentBox, SkipBar and DiffTable.

Change-Id: I188841f569c1b61ca200c8ba946584d26142c070

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

@@ -16,6 +16,9 @@ package com.google.gerrit.client.diff;
 
 import com.google.gerrit.client.patches.PatchUtil;
 import com.google.gwt.core.client.GWT;
+import com.google.gwt.core.client.Scheduler;
+import com.google.gwt.core.client.Scheduler.ScheduledCommand;
+import com.google.gwt.dom.client.Style.Unit;
 import com.google.gwt.event.dom.client.ClickEvent;
 import com.google.gwt.event.dom.client.ClickHandler;
 import com.google.gwt.resources.client.CssResource;
@@ -45,7 +48,6 @@ class SkipBar extends Composite {
   private LineWidget widget;
 
   interface SkipBarStyle extends CssResource {
-    String isLineWidget();
     String noExpand();
   }
 
@@ -80,9 +82,15 @@ class SkipBar extends Composite {
     }, ClickEvent.getType());
   }
 
-  void setWidget(LineWidget widget) {
-    this.widget = widget;
-    addStyleName(style.isLineWidget());
+  void setWidget(LineWidget lineWidget) {
+    widget = lineWidget;
+    Scheduler.get().scheduleDeferred(new ScheduledCommand(){
+      @Override
+      public void execute() {
+        getElement().getStyle().setPaddingLeft(
+            cm.getGutterElement().getOffsetWidth(), Unit.PX);
+      }
+    });
   }
 
   void setMarker(TextMarker marker, int length) {
@@ -108,8 +116,7 @@ class SkipBar extends Composite {
 
   private boolean checkAndUpdateArrows() {
     if (numSkipLines <= UP_DOWN_THRESHOLD) {
-      upArrow.addStyleName(style.noExpand());
-      downArrow.addStyleName(style.noExpand());
+      addStyleName(style.noExpand());
       return false;
     }
     return true;