prepare for singleton variant -> undefined

1. is_type_number has to be adjusted in several ways
for singleton variant -- its type is now undefined
for non-singleton variant -- it has to still be number
2. Change Lam_compile_const.Const_pointer compilation
3. Check Pisint

Author: bobzhang

jscomp/runtime/release.ninja

@@ -32,7 +32,7 @@ build runtime/caml_format.cmj : cc_cmi runtime/caml_format.ml | runtime/caml_bui
 build runtime/caml_format.cmi : cc runtime/caml_format.mli | runtime/bs_stdlib_mini.cmi runtime/js.cmi runtime/js.cmj
 build runtime/caml_gc.cmj : cc_cmi runtime/caml_gc.ml | runtime/caml_gc.cmi
 build runtime/caml_gc.cmi : cc runtime/caml_gc.mli | runtime/bs_stdlib_mini.cmi runtime/js.cmi runtime/js.cmj
-build runtime/caml_hash.cmj : cc_cmi runtime/caml_hash.ml | runtime/caml_builtin_exceptions.cmj runtime/caml_hash.cmi runtime/caml_hash_primitive.cmj runtime/caml_nativeint_extern.cmj runtime/caml_obj_extern.cmj runtime/caml_undefined_extern.cmj runtime/js.cmj
+build runtime/caml_hash.cmj : cc_cmi runtime/caml_hash.ml | runtime/caml_builtin_exceptions.cmj runtime/caml_hash.cmi runtime/caml_hash_primitive.cmj runtime/caml_nativeint_extern.cmj runtime/caml_obj_extern.cmj runtime/js.cmj
 build runtime/caml_hash.cmi : cc runtime/caml_hash.mli | runtime/bs_stdlib_mini.cmi runtime/caml_obj_extern.cmj runtime/js.cmi runtime/js.cmj
 build runtime/caml_hash_primitive.cmj : cc_cmi runtime/caml_hash_primitive.ml | runtime/caml_char.cmj runtime/caml_hash_primitive.cmi runtime/caml_int32.cmj runtime/caml_nativeint_extern.cmj runtime/caml_string_extern.cmj
 build runtime/caml_hash_primitive.cmi : cc runtime/caml_hash_primitive.mli | runtime/bs_stdlib_mini.cmi runtime/js.cmi runtime/js.cmj

jscomp/test/singular_unit_test.ml

@@ -0,0 +1,14 @@
+type t = A
+
+let f0 ( x : t) = 
+  match x with 
+  | A as y -> y
+
+let f1 (x : t) = 
+  match x with 
+  | A -> 2     
+
+let f3 x = 
+  match x with    
+  | Some (A as y) -> y
+  | None -> A