[js-api] Verify initial < maximum in Memory ctor

Fixes issue #876.

document/js-api/index.bs

@@ -573,6 +573,7 @@ which can be simultaneously referenced by multiple {{Instance}} objects. Each
     The <dfn constructor for="Memory">Memory(|descriptor|)</dfn> constructor, when invoked, performs the following steps:
     1. If |descriptor|["initial"] is [=present=], let |initial| be |descriptor|["initial"]; otherwise, let |initial| be 0.
     1. If |descriptor|["maximum"] is [=present=], let |maximum| be |descriptor|["maximum"]; otherwise, let |maximum| be empty.
+    1. If |maximum| is not empty and |maximum| &lt; |initial|, throw a {{RangeError}} exception.
     1. Let |memtype| be { min |initial|, max |maximum| }
     1. Let |store| be the [=surrounding agent=]'s [=associated store=].
     1. Let (|store|, |memaddr|) be [=alloc_mem=](|store|, |memtype|). If allocation fails, throw a {{RangeError}} exception.
@@ -662,10 +663,10 @@ which can be simultaneously referenced by multiple {{Instance}} objects. Each
 
 <div algorithm>
     The <dfn constructor for="Table">Table(|descriptor|)</dfn> constructor, when invoked, performs the following steps:
-    1. If |descriptor|["initial"] is [=present=], let |n| be |descriptor|["initial"]; otherwise, let |n| be 0.
-    1. If |descriptor|["maximum"] is [=present=], let |m| be |descriptor|["maximum"]; otherwise, let |m| be empty.
-    1. If |m| is not empty and |m| &lt; |n|, throw a {{RangeError}} exception.
-    1. Let |type| be the [=table type=] {[=table type|𝗆𝗂𝗇=] n, [=table type|𝗆𝖺𝗑=] |m|} [=table type|𝖺𝗇𝗒𝖿𝗎𝗇𝖼=].
+    1. If |descriptor|["initial"] is [=present=], let |initial| be |descriptor|["initial"]; otherwise, let |initial| be 0.
+    1. If |descriptor|["maximum"] is [=present=], let |maximum| be |descriptor|["maximum"]; otherwise, let |maximum| be empty.
+    1. If |maximum| is not empty and |maximum| &lt; |initial|, throw a {{RangeError}} exception.
+    1. Let |type| be the [=table type=] {[=table type|𝗆𝗂𝗇=] n, [=table type|𝗆𝖺𝗑=] |maximum|} [=table type|𝖺𝗇𝗒𝖿𝗎𝗇𝖼=].
     1. Let |store| be the [=surrounding agent=]'s [=associated store=].
     1. Let (|store|, |tableaddr|) be [=alloc_table=](|store|, |type|). <!-- TODO(littledan): Report allocation failure https://github.com/WebAssembly/spec/issues/584 -->
     1. Set the [=surrounding agent=]'s [=associated store=] to |store|.