Fix a bunch of spelling mistakes :\

src/parser.h

Index: src/parser.h
diff --git a/src/parser.h b/src/parser.h
index 6e86f0961ab43a8646466e66d184a0d69aa231a1..ee303b402a95ae16b2ac3ee35ca58d2116a0f355 100644
--- a/src/parser.h
+++ b/src/parser.h
@@ -153,7 +153,7 @@ bool ParseRegExp(FlatStringReader* input,
 // Support for doing lazy compilation. The script is the script containing full
 // source of the script where the function is declared. The start_position and
 // end_position specifies the part of the script source which has the source
-// for the function decleration in the form:
+// for the function declaration in the form:
 //
 //    (<formal parameters>) { <function body> }
 //