JS: Fixed variables named "async" (#1738)

Fixes variables names "async" in JS.

components/prism-javascript.js

@@ -11,7 +11,7 @@ Prism.languages.javascript = Prism.languages.extend('clike', {
 			pattern: /((?:^|})\s*)(?:catch|finally)\b/,
 			lookbehind: true
 		},
-		/\b(?:as|async|await|break|case|class|const|continue|debugger|default|delete|do|else|enum|export|extends|for|from|function|get|if|implements|import|in|instanceof|interface|let|new|null|of|package|private|protected|public|return|set|static|super|switch|this|throw|try|typeof|undefined|var|void|while|with|yield)\b/
+		/\b(?:as|async(?=\s*(?:function\b|\(|[$\w\xA0-\uFFFF]|$))|await|break|case|class|const|continue|debugger|default|delete|do|else|enum|export|extends|for|from|function|get|if|implements|import|in|instanceof|interface|let|new|null|of|package|private|protected|public|return|set|static|super|switch|this|throw|try|typeof|undefined|var|void|while|with|yield)\b/
 	],
 	'number': /\b(?:(?:0[xX][\dA-Fa-f]+|0[bB][01]+|0[oO][0-7]+)n?|\d+n|NaN|Infinity)\b|(?:\b\d+\.?\d*|\B\.\d+)(?:[Ee][+-]?\d+)?/,
 	// Allow for all non-ASCII characters (See http://stackoverflow.com/a/2008444)

prism.js

@@ -720,7 +720,7 @@ Prism.languages.javascript = Prism.languages.extend('clike', {
 			pattern: /((?:^|})\s*)(?:catch|finally)\b/,
 			lookbehind: true
 		},
-		/\b(?:as|async|await|break|case|class|const|continue|debugger|default|delete|do|else|enum|export|extends|for|from|function|get|if|implements|import|in|instanceof|interface|let|new|null|of|package|private|protected|public|return|set|static|super|switch|this|throw|try|typeof|undefined|var|void|while|with|yield)\b/
+		/\b(?:as|async(?=\s*(?:function\b|\(|[$\w\xA0-\uFFFF]|$))|await|break|case|class|const|continue|debugger|default|delete|do|else|enum|export|extends|for|from|function|get|if|implements|import|in|instanceof|interface|let|new|null|of|package|private|protected|public|return|set|static|super|switch|this|throw|try|typeof|undefined|var|void|while|with|yield)\b/
 	],
 	'number': /\b(?:(?:0[xX][\dA-Fa-f]+|0[bB][01]+|0[oO][0-7]+)n?|\d+n|NaN|Infinity)\b|(?:\b\d+\.?\d*|\B\.\d+)(?:[Ee][+-]?\d+)?/,
 	// Allow for all non-ASCII characters (See http://stackoverflow.com/a/2008444)

tests/languages/javascript/keyword_feature.test

@@ -1,10 +1,11 @@
 catch finally;
+async function;
 
-as; async; await; break; case;
+as; await; break; case;
 class; const; continue; debugger;
 default; delete; do; else; enum;
 export; extends; for;
-from; function; get; if; implements;
+from; get; if; implements;
 import; in; instanceof; interface; let;
 new; null; of; package; private;
 protected; public; return; set; static;
@@ -18,8 +19,10 @@ with; yield;
 	["keyword", "catch"],
 	["keyword", "finally"], ["punctuation", ";"],
 
+	["keyword", "async"],
+	["keyword", "function"], ["punctuation", ";"],
+
 	["keyword", "as"], ["punctuation", ";"],
-	["keyword", "async"], ["punctuation", ";"],
 	["keyword", "await"], ["punctuation", ";"],
 	["keyword", "break"], ["punctuation", ";"],
 	["keyword", "case"], ["punctuation", ";"],
@@ -36,7 +39,6 @@ with; yield;
 	["keyword", "extends"], ["punctuation", ";"],
 	["keyword", "for"], ["punctuation", ";"],
 	["keyword", "from"], ["punctuation", ";"],
-	["keyword", "function"], ["punctuation", ";"],
 	["keyword", "get"], ["punctuation", ";"],
 	["keyword", "if"], ["punctuation", ";"],
 	["keyword", "implements"], ["punctuation", ";"],

tests/languages/javascript/variable_feature.test

@@ -0,0 +1,15 @@
+let async = true;
+
+----------------------------------------------------
+
+[
+	["keyword", "let"],
+	" async ",
+	["operator", "="],
+	["boolean", "true"],
+	["punctuation", ";"]
+]
+
+----------------------------------------------------
+
+Checks for variables with special names.