Remove ctrl-d keybinding to discard comment

The ctrl-d binding is dangerous as it removes the unsaved draft comment
without confirmation and is a common keybinding when editing text (it is
the emacs binding for forward-delete). Esc can still be used to discard
unsaved draft comments; removing saved draft comments will now require
using the mouse.

Change-Id: I30120351f4be0a09ad9404d352fde1408982c05f

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

@@ -86,8 +86,6 @@ public abstract class AbstractPatchContentTable extends NavigationTable<Object>
       keysComment = new KeyCommandSet(PatchUtil.C.commentEditorSet());
       keysComment.add(new NoOpKeyCommand(KeyCommand.M_CTRL, 's', PatchUtil.C
           .commentSaveDraft()));
-      keysComment.add(new NoOpKeyCommand(KeyCommand.M_CTRL, 'd', PatchUtil.C
-          .commentDiscard()));
       keysComment.add(new NoOpKeyCommand(0, KeyCodes.KEY_ESCAPE, PatchUtil.C
           .commentCancelEdit()));
     } else {

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

@@ -102,18 +102,6 @@ public class CommentEditorPanel extends CommentPanel implements ClickHandler,
               event.preventDefault();
               onSave(NULL_CALLBACK);
               return;
-
-            case 'd':
-            case 'D':
-              event.preventDefault();
-              if (isNew()) {
-                onDiscard();
-              } else if (Window.confirm(PatchUtil.C.confirmDiscard())) {
-                onDiscard();
-              } else {
-                text.setFocus(true);
-              }
-              return;
           }
         }
 

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

@@ -24,7 +24,6 @@ public interface PatchConstants extends Constants {
   String buttonSave();
   String buttonCancel();
   String buttonDiscard();
-  String confirmDiscard();
 
   String noDifference();
   String patchHeaderOld();
@@ -46,7 +45,6 @@ public interface PatchConstants extends Constants {
   String commentEditorSet();
   String commentInsert();
   String commentSaveDraft();
-  String commentDiscard();
   String commentCancelEdit();
 
   String whitespaceIGNORE_NONE();

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

@@ -7,7 +7,6 @@ buttonEdit = Edit
 buttonSave = Save
 buttonCancel = Cancel
 buttonDiscard = Discard
-confirmDiscard = Discard this comment?
 
 noDifference = No Differences
 patchHeaderOld = Old Version
@@ -28,7 +27,6 @@ expandComment = Expand or collapse comment
 commentEditorSet = Comment Editing
 commentInsert = Create a new inline comment
 commentSaveDraft = Save draft comment
-commentDiscard = Discard draft comment
 commentCancelEdit = Cancel comment edit
 
 whitespaceIGNORE_NONE=None