Bug 1225192 - remove leading whitespace before prettifying css; r=pbrosset

devtools/shared/styleinspector/css-logic.js

@@ -978,11 +978,13 @@ CssLogic.prettifyCSS = function(text, ruleCount) {
 
   // remove initial and terminating HTML comments and surrounding whitespace
   text = text.replace(/(?:^\s*<!--[\r\n]*)|(?:\s*-->\s*$)/g, "");
+  let originalText = text;
+  text = text.trim();
 
   // don't attempt to prettify if there's more than one line per rule.
   let lineCount = text.split("\n").length - 1;
   if (ruleCount !== null && lineCount >= ruleCount) {
-    return text;
+    return originalText;
   }
 
   // We reformat the text using a simple state machine.  The
@@ -1139,7 +1141,7 @@ CssLogic.prettifyCSS = function(text, ruleCount) {
     // the text.
     if (pushbackToken && token && token.tokenType === "whitespace" &&
         /\n/g.test(text.substring(token.startOffset, token.endOffset))) {
-      return text;
+      return originalText;
     }
 
     // Finally time for that newline.

devtools/shared/tests/unit/test_prettifyCSS.js

@@ -7,7 +7,6 @@
 
 const {CssLogic} = require("devtools/shared/styleinspector/css-logic");
 
-
 const TESTS = [
   { name: "simple test",
     input: "div { font-family:'Arial Black', Arial, sans-serif; }",
@@ -29,7 +28,6 @@ const TESTS = [
   { name: "minified with trailing newline",
     input: "\nbody{background:white;}div{font-size:4em;color:red}span{color:green;}\n",
     expected: [
-      "",
       "body {",
       "\tbackground:white;",
       "}",
@@ -43,6 +41,14 @@ const TESTS = [
     ]
   },
 
+  { name: "leading whitespace",
+    input: "\n    div{color: red;}",
+    expected: [
+      "div {",
+      "\tcolor: red;",
+      "}"
+    ]
+  },
 ];
 
 function run_test() {