Bug 1419301 - Make HTML comments removal in prettifyCSS faster; r=tromey

MozReview-Commit-ID: LG8GKccRlXr

--HG--
extra : rebase_source : 86eb5612f8264bbe4f765ab5baaea4db8c7a84a3

devtools/shared/inspector/css-logic.js

@@ -158,8 +158,13 @@ function prettifyCSS(text, ruleCount) {
     prettifyCSS.LINE_SEPARATOR = (os === "WINNT" ? "\r\n" : "\n");
   }
 
-  // remove initial and terminating HTML comments and surrounding whitespace
+  // Stylesheets may start and end with HTML comment tags (possibly with whitespaces
-  text = text.replace(/(?:^\s*<!--[\r\n]*)|(?:\s*-->\s*$)/g, "");
+  // before and after). Remove those first. Don't do anything there aren't any.
+  let trimmed = text.trim();
+  if (trimmed.startsWith("<!--")) {
+    text = trimmed.replace(/^<!--/, "").replace(/-->$/, "").trim();
+  }
+
   let originalText = text;
   text = text.trim();
 

devtools/shared/tests/unit/test_prettifyCSS.js

@@ -122,6 +122,24 @@ const TESTS_SPACE_INDENT = [
       "}",
     ]
   },
+
+  { name: "HTML comments with some whitespace padding",
+    input: "  \n\n\t  <!--\n\n\t body {color:red}  \n\n-->   \t\n",
+    expected: [
+      "body {",
+      " color:red",
+      "}"
+    ]
+  },
+
+  { name: "HTML comments without whitespace padding",
+    input: "<!--body {color:red}-->",
+    expected: [
+      "body {",
+      " color:red",
+      "}"
+    ]
+  },
 ];
 
 function run_test() {