remove dictmaker rule; it's unused

Grammar/Grammar

@@ -114,7 +114,6 @@ subscript: '.' '.' '.' | test | [test] ':' [test] [sliceop]
 sliceop: ':' [test]
 exprlist: expr (',' expr)* [',']
 testlist: test (',' test)* [',']
-dictmaker: test ':' test (',' test ':' test)* [',']
 dictorsetmaker: ( (test ':' test (comp_for | (',' test ':' test)* [','])) |
                   (test (comp_for | (',' test)* [','])) )
 

Include/graminit.h

@@ -72,17 +72,16 @@
 #define sliceop 325
 #define exprlist 326
 #define testlist 327
-#define dictmaker 328
-#define dictorsetmaker 329
-#define classdef 330
-#define arglist 331
-#define argument 332
-#define list_iter 333
-#define list_for 334
-#define list_if 335
-#define comp_iter 336
-#define comp_for 337
-#define comp_if 338
-#define testlist1 339
-#define encoding_decl 340
-#define yield_expr 341
+#define dictorsetmaker 328
+#define classdef 329
+#define arglist 330
+#define argument 331
+#define list_iter 332
+#define list_for 333
+#define list_if 334
+#define comp_iter 335
+#define comp_for 336
+#define comp_if 337
+#define testlist1 338
+#define encoding_decl 339
+#define yield_expr 340

Misc/NEWS

@@ -9,6 +9,8 @@ What's New in Python 2.7.2?
 Core and Builtins
 -----------------
 
+- Issue #10674: Remove unused 'dictmaker' rule from grammar.
+
 - Issue #10596: Fix float.__mod__ to have the same behaviour as
   float.__divmod__ with respect to signed zeros.  -4.0 % 4.0 should be
   0.0, not -0.0.