Revert "rustdoc: Move collapse toggle to the left"

This reverts commit 0885865.

Author: vi

src/librustdoc/html/static/rustdoc.css

@@ -695,7 +695,7 @@ a.test-arrow:hover{
 .collapse-toggle {
 	font-weight: 300;
 	position: absolute;
-	left: -40px;
+	left: -23px;
 	top: 0;
 }