Code review. Minor fixes - fixed typo and made a test more readable

Author: andrykonchin

spec/ruby/core/regexp/source_spec.rb

@@ -10,7 +10,7 @@
   end
 
   it "keeps escape sequences as is" do
-    /\x20\+/.source.should == "\\x20\\+"
+    /\x20\+/.source.should == '\x20\+'
   end
 
   describe "escaping" do

src/main/java/org/truffleruby/parser/parser/ParserSupport.java

@@ -645,7 +645,7 @@ private void handleUselessWarn(ParseNode node, String useless) {
                 "Useless use of " + useless + " in void context.");
     }
 
-    /** Check to see if current node is a useless statement. If useless a warning if printed.
+    /** Check to see if current node is a useless statement. If useless a warning is printed.
      *
      * @param node to be checked. */
     public void checkUselessStatement(ParseNode node) {