rustdoc: simplify CSS for codeblock tooltips

Instead of making its parts `display: none` and then changing it on hover,
just make the pseudo-element itself on hover.

Author: notriddle

src/librustdoc/html/static/css/rustdoc.css

@@ -1114,8 +1114,7 @@ pre.rust .doccomment {
 	top: 5px;
 }
 
-.example-wrap .tooltip::after {
-	display: none;
+.example-wrap .tooltip:hover::after {
 	text-align: center;
 	padding: 5px 3px 3px 3px;
 	border-radius: 6px;
@@ -1130,35 +1129,30 @@ pre.rust .doccomment {
 	color: var(--tooltip-color);
 }
 
-.example-wrap .tooltip::before {
+.example-wrap .tooltip:hover::before {
 	content: " ";
 	position: absolute;
 	top: 50%;
 	left: 16px;
 	margin-top: -5px;
-	display: none;
 	z-index: 1;
 	border: 5px solid transparent;
 	border-right-color: var(--tooltip-background-color);
 }
 
-.example-wrap.ignore .tooltip::after {
+.example-wrap.ignore .tooltip:hover::after {
 	content: "This example is not tested";
 }
-.example-wrap.compile_fail .tooltip::after {
+.example-wrap.compile_fail .tooltip:hover::after {
 	content: "This example deliberately fails to compile";
 }
-.example-wrap.should_panic .tooltip::after {
+.example-wrap.should_panic .tooltip:hover::after {
 	content: "This example panics";
 }
-.example-wrap.edition .tooltip::after {
+.example-wrap.edition .tooltip:hover::after {
 	content: "This code runs with edition " attr(data-edition);
 }
 
-.example-wrap .tooltip:hover::before, .example-wrap .tooltip:hover::after {
-	display: inline;
-}
-
 .example-wrap.compile_fail .tooltip,
 .example-wrap.should_panic .tooltip,
 .example-wrap.ignore .tooltip {

src/test/rustdoc-gui/codeblock-tooltip.goml

@@ -20,7 +20,7 @@ define-function: (
             {"border-left": "2px solid rgba(255, 0, 0, 0.5)"},
         )),
 
-        ("move-cursor-to", ".docblock .example-wrap.compile_fail"),
+        ("move-cursor-to", ".docblock .example-wrap.compile_fail .tooltip"),
 
         ("assert-css", (
             ".docblock .example-wrap.compile_fail .tooltip",
@@ -60,7 +60,7 @@ define-function: (
             {"border-left": "2px solid rgba(255, 0, 0, 0.5)"},
         )),
 
-        ("move-cursor-to", ".docblock .example-wrap.should_panic"),
+        ("move-cursor-to", ".docblock .example-wrap.should_panic .tooltip"),
 
         ("assert-css", (
             ".docblock .example-wrap.should_panic .tooltip",
@@ -100,7 +100,7 @@ define-function: (
             {"border-left": "2px solid rgba(255, 142, 0, 0.6)"},
         )),
 
-        ("move-cursor-to", ".docblock .example-wrap.ignore"),
+        ("move-cursor-to", ".docblock .example-wrap.ignore .tooltip"),
 
         ("assert-css", (
             ".docblock .example-wrap.ignore .tooltip",