[interpreter] Remove duplicated token declarations.

This patch tidies up the `parser.mly` module by removing two instances
of `%prec` that were never useful. More importantly, this patch also
removes duplicated token declarations as `menhir` considers such an
error in debug mode. Consequently, it is now possible to debug the
grammar using `menhir --explain` or similar.

interpreter/text/parser.mly

@@ -205,70 +205,40 @@ let inline_type_explicit (c : context) x ft at =
 %}
 
 %token LPAR RPAR
-%token NAT INT FLOAT STRING VAR
-%token NUM_TYPE VEC_TYPE VEC_SHAPE FUNCREF EXTERNREF EXTERN MUT
+%token<string> NAT INT FLOAT STRING VAR
+%token<Types.num_type> NUM_TYPE
+%token<Types.vec_type> VEC_TYPE
+%token<V128.shape> VEC_SHAPE
+%token FUNCREF EXTERNREF EXTERN MUT
 %token UNREACHABLE NOP DROP SELECT
 %token BLOCK END IF THEN ELSE LOOP BR BR_IF BR_TABLE
 %token CALL CALL_INDIRECT RETURN
 %token LOCAL_GET LOCAL_SET LOCAL_TEE GLOBAL_GET GLOBAL_SET
 %token TABLE_GET TABLE_SET
 %token TABLE_SIZE TABLE_GROW TABLE_FILL TABLE_COPY TABLE_INIT ELEM_DROP
 %token MEMORY_SIZE MEMORY_GROW MEMORY_FILL MEMORY_COPY MEMORY_INIT DATA_DROP
-%token LOAD STORE OFFSET_EQ_NAT ALIGN_EQ_NAT
-%token CONST UNARY BINARY TEST COMPARE CONVERT
+%token<int option -> Memory.offset -> Ast.instr'> LOAD STORE
+%token<string> OFFSET_EQ_NAT ALIGN_EQ_NAT
+%token<string Source.phrase -> Ast.instr' * Values.num> CONST
+%token<Ast.instr'> UNARY BINARY TEST COMPARE CONVERT
 %token REF_NULL REF_FUNC REF_EXTERN REF_IS_NULL
-%token VEC_LOAD VEC_STORE VEC_LOAD_LANE VEC_STORE_LANE
-%token VEC_CONST VEC_UNARY VEC_BINARY VEC_TERNARY VEC_TEST
-%token VEC_SHIFT VEC_BITMASK VEC_SHUFFLE
-%token VEC_EXTRACT VEC_REPLACE
+%token<int option -> Memory.offset -> Ast.instr'> VEC_LOAD VEC_STORE
+%token<int option -> Memory.offset -> int -> Ast.instr'> VEC_LOAD_LANE VEC_STORE_LANE
+%token<V128.shape -> string Source.phrase list -> Source.region -> Ast.instr' * Values.vec> VEC_CONST
+%token<Ast.instr'> VEC_UNARY VEC_BINARY VEC_TERNARY VEC_TEST
+%token<Ast.instr'> VEC_SHIFT VEC_BITMASK VEC_SPLAT
+%token VEC_SHUFFLE
+%token<int -> Ast.instr'> VEC_EXTRACT VEC_REPLACE
 %token FUNC START TYPE PARAM RESULT LOCAL GLOBAL
 %token TABLE ELEM MEMORY DATA DECLARE OFFSET ITEM IMPORT EXPORT
 %token MODULE BIN QUOTE
 %token SCRIPT REGISTER INVOKE GET
-%token ASSERT_MALFORMED ASSERT_INVALID ASSERT_SOFT_INVALID ASSERT_UNLINKABLE
+%token ASSERT_MALFORMED ASSERT_INVALID ASSERT_UNLINKABLE
 %token ASSERT_RETURN ASSERT_TRAP ASSERT_EXHAUSTION
-%token NAN
+%token<Script.nan> NAN
 %token INPUT OUTPUT
 %token EOF
 
-%token<string> NAT
-%token<string> INT
-%token<string> FLOAT
-%token<string> STRING
-%token<string> VAR
-%token<Types.num_type> NUM_TYPE
-%token<Types.vec_type> VEC_TYPE
-%token<string Source.phrase -> Ast.instr' * Values.num> CONST
-%token<V128.shape -> string Source.phrase list -> Source.region -> Ast.instr' * Values.vec> VEC_CONST
-%token<Ast.instr'> UNARY
-%token<Ast.instr'> BINARY
-%token<Ast.instr'> TEST
-%token<Ast.instr'> COMPARE
-%token<Ast.instr'> CONVERT
-%token<int option -> Memory.offset -> Ast.instr'> LOAD
-%token<int option -> Memory.offset -> Ast.instr'> STORE
-%token<int option -> Memory.offset -> Ast.instr'> VEC_LOAD
-%token<int option -> Memory.offset -> Ast.instr'> VEC_STORE
-%token<int option -> Memory.offset -> int -> Ast.instr'> VEC_LOAD_LANE
-%token<int option -> Memory.offset -> int -> Ast.instr'> VEC_STORE_LANE
-%token<Ast.instr'> VEC_UNARY
-%token<Ast.instr'> VEC_BINARY
-%token<Ast.instr'> VEC_TERNARY
-%token<Ast.instr'> VEC_TEST
-%token<Ast.instr'> VEC_SHIFT
-%token<Ast.instr'> VEC_BITMASK
-%token<Ast.instr'> VEC_SPLAT
-%token<int -> Ast.instr'> VEC_EXTRACT
-%token<int -> Ast.instr'> VEC_REPLACE
-%token<string> OFFSET_EQ_NAT
-%token<string> ALIGN_EQ_NAT
-%token<V128.shape> VEC_SHAPE
-
-%token<Script.nan> NAN
-
-%nonassoc LOW
-%nonassoc VAR
-
 %start script script1 module1
 %type<Script.script> script
 %type<Script.script> script1
@@ -367,7 +337,7 @@ bind_var :
   | VAR { $1 @@ at () }
 
 labeling_opt :
-  | /* empty */ %prec LOW
+  | /* empty */
     { fun c xs ->
       List.iter (fun x -> error x.at "mismatching label") xs;
       anon_label c }
@@ -378,7 +348,7 @@ labeling_opt :
       bind_label c $1 }
 
 labeling_end_opt :
-  | /* empty */ %prec LOW { [] }
+  | /* empty */ { [] }
   | bind_var { [$1] }
 
 offset_opt :