Speed up whitespace handling

stdx/d/lexer.d

@@ -581,8 +581,9 @@ public struct DLexer(R)
 				break loop;
 			}
 		} while (!range.empty);
-		return Token(tok!"whitespace", cache.cacheGet(range.slice(mark)), line,
-			column, index);
+		string text = config.whitespaceBehavior == WhitespaceBehavior.skip
+			? null : cache.cacheGet(range.slice(mark));
+		return Token(tok!"whitespace", text, line, column, index);
 	}
 
 	Token lexNumber() pure nothrow

stdx/lexer.d

@@ -272,8 +272,6 @@ mixin template Lexer(R, IDType, Token, alias defaultTokenFunction,
 	Token _front;
 }
 
-debug = 1;
-
 struct LexerRange(BufferType) if (isBuffer!BufferType)
 {
 	this(BufferType r)