[dash] Move BackLink to CSS

The previous commit 626f679947 broke the back links on
search drilldown.

https://bugzilla.gnome.org/show_bug.cgi?id=601413

data/Makefile.am

@@ -16,7 +16,6 @@ imagesdir = $(pkgdatadir)/images
 dist_images_DATA =				\
 	add-workspace.svg			\
 	app-well-glow.png			\
-	back.svg				\
 	close.svg				\
 	close-black.svg				\
 	info.svg				\
@@ -30,7 +29,8 @@ dist_theme_DATA =				\
 	theme/scroll-button-down-hover.png	\
 	theme/scroll-button-up.png		\
 	theme/scroll-button-up-hover.png	\
-	theme/scroll-vhandle.png
+	theme/scroll-vhandle.png        \
+	theme/section-back.svg
 
 schemadir  = @GCONF_SCHEMA_FILE_DIR@
 schema_DATA = gnome-shell.schemas

data/theme/gnome-shell.css

@@ -101,12 +101,24 @@ StScrollBar StButton#vhandle:hover
 .section-header-inner {
     border: 1px solid #000000;
     padding: 0px 4px;
+    spacing: 4px;
 }
 
 .section-text-content {
     padding: 4px 0px;
 }
 
+.section-header-back {
+    padding: 0px 4px 0px 0px;
+    border-right: 1px solid #262626;
+}
+
+.section-header-back-image {
+    background-image: url("section-back.svg");
+    width: 12px;
+    height: 16px;
+}
+
 .section-count {
 }