Preserve line-endings in inline editing

When a file with Windows line endings was edited all the line ending
characters were replaced by the Unix style line endings '\n'. This
generated artificially large diffs as all lines had a changed line
ending.

To solve the issue this change automatically detects the line-ending
type and preserves line-endings by setting an option parameter of the
editor called "lineSeperator".

Bug: issue 3345
Change-Id: If7e2ed3b3327c7734175f1d3e864deaae2401a8f

gerrit-gwtui/src/main/java/com/google/gerrit/client/editor/EditScreen.java

@@ -558,7 +558,7 @@ public class EditScreen extends Screen {
         mode = ModeInfo.findMode(content.getContentType(), path);
       }
     }
-    mv = MergeView.create(editor, Configuration.create()
+    Configuration cfg = Configuration.create()
         .set("autoCloseBrackets", prefs.autoCloseBrackets())
         .set("cursorBlinkRate", prefs.cursorBlinkRate())
         .set("cursorHeight", 0.85)
@@ -574,7 +574,13 @@ public class EditScreen extends Screen {
         .set("styleSelectedText", true)
         .set("tabSize", prefs.tabSize())
         .set("theme", prefs.theme().name().toLowerCase())
-        .set("value", ""));
+        .set("value", "");
+
+    if (editContent.contains("\r\n")) {
+      cfg.set("lineSeparator", "\r\n");
+    }
+
+    mv = MergeView.create(editor, cfg);
 
     cmBase = mv.leftOriginal();
     cmBase.getWrapperElement().addClassName(style.base());