Throw TypeError for shared memory w/o maximum (#154)

Instead of RangeError.

Fixes #153.

document/js-api/index.bs

@@ -657,7 +657,7 @@ which can be simultaneously referenced by multiple {{Instance}} objects. Each
     1. If |descriptor|["maximum"] is [=present=], let |maximum| be |descriptor|["maximum"]; otherwise, let |maximum| be empty.
     1. If |maximum| is not empty and |maximum| < |initial|, throw a {{RangeError}} exception.
     1. Let |shared| be |descriptor|["shared"].
-    1. If |shared| is true and |maximum| is empty, throw a {{RangeError}} exception.
+    1. If |shared| is true and |maximum| is empty, throw a {{TypeError}} exception.
     1. Let |memtype| be { min |initial|, max |maximum|, shared |shared| }
     1. Let |store| be the [=surrounding agent=]'s [=associated store=].
     1. Let (|store|, |memaddr|) be [=mem_alloc=](|store|, |memtype|). If allocation fails, throw a {{RangeError}} exception.