Smalltalk: Allowed empty strings and comments (#1747)

This fixes that empty strings and comments were not recognized in Smalltalk.

Author: RunDevelopment

components/prism-smalltalk.js

@@ -1,6 +1,6 @@
 Prism.languages.smalltalk = {
-	'comment': /"(?:""|[^"])+"/,
-	'string': /'(?:''|[^'])+'/,
+	'comment': /"(?:""|[^"])*"/,
+	'string': /'(?:''|[^'])*'/,
 	'symbol': /#[\da-z]+|#(?:-|([+\/\\*~<>=@%|&?!])\1?)|#(?=\()/i,
 	'block-arguments': {
 		pattern: /(\[\s*):[^\[|]*\|/,
@@ -28,4 +28,4 @@ Prism.languages.smalltalk = {
 	],
 	'operator': /[<=]=?|:=|~[~=]|\/\/?|\\\\|>[>=]?|[!^+\-*&|,@]/,
 	'punctuation': /[.;:?\[\](){}]/
-};
+};

components/prism-smalltalk.min.js

@@ -1,14 +1,16 @@
 "foobar"
 "foo""bar
 baz"
+""
 
 ----------------------------------------------------
 
 [
 	["comment", "\"foobar\""],
-	["comment", "\"foo\"\"bar\r\nbaz\""]
+	["comment", "\"foo\"\"bar\r\nbaz\""],
+	["comment", "\"\""]
 ]
 
 ----------------------------------------------------
 
-Checks for comments.
+Checks for comments.

tests/languages/smalltalk/comment_feature.test

@@ -1,14 +1,16 @@
 'foobar'
 'foo''bar
 baz'
+''
 
 ----------------------------------------------------
 
 [
 	["string", "'foobar'"],
-	["string", "'foo''bar\r\nbaz'"]
+	["string", "'foo''bar\r\nbaz'"],
+	["string", "''"]
 ]
 
 ----------------------------------------------------
 
-Checks for strings.
+Checks for strings.