Tweak some display behaviors for indent indicators

Summary:
Ref T13161.

  - Don't show ">>" when the line indentation changed but the text also changed, this is just "the line changed".
  - The indicator seems a little cleaner if we just reuse the existing "bright" colors, which already have colorblind colors anyway.

Test Plan: Got slightly better rendering for some diffs locally.

Reviewers: amckinley

Reviewed By: amckinley

Maniphest Tasks: T13161

Differential Revision: https://secure.phabricator.com/D20195

src/applications/celerity/postprocessor/CelerityDefaultPostprocessor.php

@@ -199,10 +199,8 @@ final class CelerityDefaultPostprocessor
       'diff.background' => '#fff',
       'new-background' => 'rgba(151, 234, 151, .3)',
       'new-bright' => 'rgba(151, 234, 151, .6)',
-      'new-background-strong' => 'rgba(151, 234, 151, 1)',
       'old-background' => 'rgba(251, 175, 175, .3)',
       'old-bright' => 'rgba(251, 175, 175, .7)',
-      'old-background-strong' => 'rgba(251, 175, 175, 1)',
       'move-background' => '#fdf5d4',
       'copy-background' => '#f1c40f',
 

src/applications/differential/parser/DifferentialHunkParser.php

@@ -288,7 +288,7 @@ final class DifferentialHunkParser extends Phobject {
         $o_text = $o['text'];
         $n_text = $n['text'];
 
-        if ($o_text !== $n_text) {
+        if ($o_text !== $n_text && (ltrim($o_text) === ltrim($n_text))) {
           $o_depth = $this->getIndentDepth($o_text, $tab_width);
           $n_depth = $this->getIndentDepth($n_text, $tab_width);