Prolog: Removed variable token + minor improvements (#3247)

components/prism-prolog.js

@@ -1,16 +1,15 @@
 Prism.languages.prolog = {
 	// Syntax depends on the implementation
-	'comment': [
-		/%.+/,
-		/\/\*[\s\S]*?\*\//
-	],
+	'comment': {
+		pattern: /\/\*[\s\S]*?\*\/|%.*/,
+		greedy: true
+	},
 	// Depending on the implementation, strings may allow escaped newlines and quote-escape
 	'string': {
-		pattern: /(["'])(?:\1\1|\\(?:\r\n|[\s\S])|(?!\1)[^\\\r\n])*\1/,
+		pattern: /(["'])(?:\1\1|\\(?:\r\n|[\s\S])|(?!\1)[^\\\r\n])*\1(?!\1)/,
 		greedy: true
 	},
 	'builtin': /\b(?:fx|fy|xf[xy]?|yfx?)\b/,
-	'variable': /\b[A-Z_]\w*/,
 	// FIXME: Should we list all null-ary predicates (not followed by a parenthesis) like halt, trace, etc.?
 	'function': /\b[a-z]\w*(?:(?=\()|\/\d+)/,
 	'number': /\b\d+(?:\.\d*)?/,