IDL parser: clean up cached lexer table updating code

Source/bindings/scripts/blink_idl_lexer.py

Index: Source/bindings/scripts/blink_idl_lexer.py
diff --git a/Source/bindings/scripts/blink_idl_lexer.py b/Source/bindings/scripts/blink_idl_lexer.py
index 6bf439641fd3a7e4dfbca8e8024c09e5e95311ed..ba68c6c7dce1f27fee35f768d536401abfe5520b 100644
--- a/Source/bindings/scripts/blink_idl_lexer.py
+++ b/Source/bindings/scripts/blink_idl_lexer.py
@@ -69,6 +69,7 @@ tools_dir = os.path.join(third_party, os.pardir, 'tools')
 sys.path.append(tools_dir)
 from idl_parser.idl_lexer import IDLLexer
 
+LEXTAB = 'lextab'
 REMOVE_TOKENS = ['COMMENT']
 
 
@@ -100,20 +101,15 @@ class BlinkIDLLexer(IDLLexer):
             sys.path.append(outputdir)
 
             if rewrite_tables:
-                tablefile = os.path.join(outputdir, 'lextab.py')
-
-                def unlink(filename):
+                tablefile_root = os.path.join(outputdir, LEXTAB)
+                # Also remove the .pyc/.pyo files, or they'll be used even if
+                # the .py file doesn't exist.
+                for ext in ('.py', '.pyc', '.pyo'):
                     try:
-                        os.unlink(filename)
+                        os.unlink(tablefile_root + ext)
                     except OSError:
                         pass
 
-                unlink(tablefile)
-                # Also remove the .pyc/.pyo files, or they'll be used even if
-                # the .py file doesn't exist.
-                unlink(tablefile + 'c')
-                unlink(tablefile + 'o')
-
         IDLLexer.__init__(self)
         # Overrides to parent class
         self._RemoveTokens(REMOVE_TOKENS)
@@ -124,7 +120,7 @@ class BlinkIDLLexer(IDLLexer):
         self._lexobj = lex.lex(object=self,
                                debug=debug,
                                optimize=optimize,
-                               lextab='lextab',
+                               lextab=LEXTAB,
                                outputdir=outputdir)