JS: Better regex detection (#2158)

This improves the detection of regular expressions.

components/prism-javascript.js

@@ -26,7 +26,7 @@ Prism.languages.javascript['class-name'][0].pattern = /(\b(?:class|interface|ext
 
 Prism.languages.insertBefore('javascript', 'keyword', {
 	'regex': {
-		pattern: /((?:^|[^$\w\xA0-\uFFFF."'\])\s])\s*)\/(?:\[(?:[^\]\\\r\n]|\\.)*]|\\.|[^/\\\[\r\n])+\/[gimyus]{0,6}(?=\s*(?:$|[\r\n,.;})\]]))/,
+		pattern: /((?:^|[^$\w\xA0-\uFFFF."'\])\s])\s*)\/(?:\[(?:[^\]\\\r\n]|\\.)*]|\\.|[^/\\\[\r\n])+\/[gimyus]{0,6}(?=(?:\s|\/\*[\s\S]*?\*\/)*(?:$|[\r\n,.;:})\]]|\/\/))/,
 		lookbehind: true,
 		greedy: true
 	},

prism.js

@@ -866,7 +866,7 @@ Prism.languages.javascript['class-name'][0].pattern = /(\b(?:class|interface|ext
 
 Prism.languages.insertBefore('javascript', 'keyword', {
 	'regex': {
-		pattern: /((?:^|[^$\w\xA0-\uFFFF."'\])\s])\s*)\/(?:\[(?:[^\]\\\r\n]|\\.)*]|\\.|[^/\\\[\r\n])+\/[gimyus]{0,6}(?=\s*(?:$|[\r\n,.;})\]]))/,
+		pattern: /((?:^|[^$\w\xA0-\uFFFF."'\])\s])\s*)\/(?:\[(?:[^\]\\\r\n]|\\.)*]|\\.|[^/\\\[\r\n])+\/[gimyus]{0,6}(?=(?:\s|\/\*[\s\S]*?\*\/)*(?:$|[\r\n,.;:})\]]|\/\/))/,
 		lookbehind: true,
 		greedy: true
 	},

tests/languages/javascript/regex_feature.test

@@ -9,6 +9,9 @@
 / '1' '2' '3' '4' '5' /
 [/foo/]
 
+let a = /regex/m // comment
+let b = condition ? /regex/ : /another one/
+
 ----------------------------------------------------
 
 [
@@ -21,7 +24,21 @@
 	["regex", "/[\\]/]/"], ["punctuation", ";"],
 	["number", "1"], ["operator", "/"], ["number", "4"], ["operator", "+"], ["string", "\"/, not a regex\""], ["punctuation", ";"],
 	["regex", "/ '1' '2' '3' '4' '5' /"],
-	["punctuation", "["], ["regex", "/foo/"], ["punctuation", "]"]
+	["punctuation", "["], ["regex", "/foo/"], ["punctuation", "]"],
+
+	["keyword", "let"],
+	" a ",
+	["operator", "="],
+	["regex", "/regex/m"],
+	["comment", "// comment"],
+	["keyword", "let"],
+	" b ",
+	["operator", "="],
+	" condition ",
+	["operator", "?"],
+	["regex", "/regex/"],
+	["operator", ":"],
+	["regex", "/another one/"]
 ]
 
 ----------------------------------------------------