Unified: Adjust brightness icon again

The change is requested by UX.

TEST=manual
BUG=879794

Change-Id: Ibea68c353d20aa81cabe4e2ee5d8fe14d48a72c4
Reviewed-on: https://chromium-review.googlesource.com/1215429Reviewed-by: Evan Stade <estade@chromium.org>
Commit-Queue: Tetsui Ohkubo <tetsui@chromium.org>
Cr-Commit-Position: refs/heads/master@{#590148}

ash/resources/vector_icons/unified_menu_brightness.icon

@@ -38,16 +38,4 @@ R_LINE_TO, 2, 2,
 R_LINE_TO, 2, -2,
 R_H_LINE_TO, 2,
 R_V_LINE_TO, -2,
-CLOSE,
-R_MOVE_TO, -4, 1,
-R_CUBIC_TO, -1.66f, 0, -3, -1.34f, -3, -3,
-R_CUBIC_TO, 0, -1.66f, 1.34f, -3, 3, -3,
-R_CUBIC_TO, 1.66f, 0, 3, 1.34f, 3, 3,
-R_CUBIC_TO, 0, 1.66f, -1.34f, 3, -3, 3,
-CLOSE,
-R_MOVE_TO, 0, -1.75f,
-R_CUBIC_TO, 0.69f, 0, 1.25f, -0.56f, 1.25f, -1.25f,
-R_CUBIC_TO, 0, -0.69f, -0.56f, -1.25f, -1.25f, -1.25f,
-R_CUBIC_TO, -0.69f, 0, -1.25f, 0.56f, -1.25f, 1.25f,
-R_CUBIC_TO, 0, 0.69f, 0.56f, 1.25f, 1.25f, 1.25f,
 CLOSE