[js-api] More subtyping removal. (WebAssembly#96)

* [js-api] Link to the fork for the core specification.

* [js-api] More subtyping removal.

* [js-api] Fix bugs in Table constructor.

* Add an assertion to ToWebAssemblyValue.

Author: Ms2ger

document/js-api/index.bs

@@ -91,7 +91,7 @@ urlPrefix: https://tc39.github.io/ecma262/; spec: ECMASCRIPT
         text: IterableToList; url: sec-iterabletolist
     type: abstract-op
         text: CreateMethodProperty; url: sec-createmethodproperty
-urlPrefix: https://webassembly.github.io/spec/core/; spec: WebAssembly; type: dfn
+urlPrefix: https://webassembly.github.io/reference-types/core/; spec: WebAssembly; type: dfn
     url: valid/modules.html#valid-module
         text: valid
         text: WebAssembly module validation
@@ -110,6 +110,7 @@ urlPrefix: https://webassembly.github.io/spec/core/; spec: WebAssembly; type: df
         text: f64.const
         text: ref.null
         text: ref.func
+        text: ref.extern
     text: function index; url: syntax/modules.html#syntax-funcidx
     text: function instance; url: exec/runtime.html#function-instances
     text: store_init; url: appendix/embedding.html#embed-store-init
@@ -145,6 +146,7 @@ urlPrefix: https://webassembly.github.io/spec/core/; spec: WebAssembly; type: df
     text: function address; url: exec/runtime.html#syntax-funcaddr
     text: memory address; url: exec/runtime.html#syntax-memaddr
     text: global address; url: exec/runtime.html#syntax-globaladdr
+    text: extern address; url: exec/runtime.html#syntax-externaddr
     url: syntax/types.html#syntax-numtype
         text: i32
         text: i64
@@ -254,7 +256,7 @@ Each [=agent=] is associated with the following [=ordered map=]s:
     * The <dfn>Table object cache</dfn>, mapping [=table address=]es to {{Table}} objects.
     * The <dfn>Exported Function cache</dfn>, mapping [=function address=]es to [=Exported Function=] objects.
     * The <dfn>Global object cache</dfn>, mapping [=global address=]es to {{Global}} objects.
-    * The <dfn>Host value cache</dfn>, mapping [=host address=]es to values.
+    * The <dfn>Extern value cache</dfn>, mapping [=extern address=]es to values.
 
 <h2 id="webassembly-namespace">The WebAssembly Namespace</h2>
 
@@ -754,15 +756,15 @@ Each {{Table}} object has the following internal slots:
 
 <div algorithm>
     The <dfn constructor for="Table">Table(|descriptor|, |value|)</dfn> constructor, when invoked, performs the following steps:
-    1. Let |elementType| be ToValueType(descriptor|["element"]).
+    1. Let |elementType| be [=ToValueType=](|descriptor|["element"]).
     1. let |initial| be |descriptor|["initial"].
     1. If |descriptor|["maximum"] [=map/exists=], 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. If |value| is missing,
         1. Let |ref| be [=DefaultValue=](|elementType|).
     1. Otherwise,
         1. Let |ref| be ? [=ToWebAssemblyValue=](|value|, |elementType|).
-    1. Let |type| be the [=table type=] {[=table type|min=] |initial|, [=table type|ma𝗑=] |maximum|} [=table type|an𝗒func=].
+    1. Let |type| be the [=table type=] {[=table type|min=] |initial|, [=table type|ma𝗑=] |maximum|} |elementType|.
     1. Let |store| be the [=surrounding agent=]'s [=associated store=].
     1. Let (|store|, |tableaddr|) be [=table_alloc=](|store|, |type|, |ref|). <!-- TODO(littledan): Report allocation failure https://github.com/WebAssembly/spec/issues/584 -->
     1. Set the [=surrounding agent=]'s [=associated store=] to |store|.
@@ -1065,20 +1067,20 @@ The algorithm <dfn>ToJSValue</dfn>(|w|) coerces a [=WebAssembly value=] to a Jav
 1. If |w| is of the form [=i32.const=] |i32|, return [=the Number value=] for [=signed_32=](|i32|).
 1. If |w| is of the form [=f32.const=] |f32|, return [=the Number value=] for |f32|.
 1. If |w| is of the form [=f64.const=] |f64|, return [=the Number value=] for |f64|.
-1. If |w| is of the form [=ref.null=], return null.
+1. If |w| is of the form [=ref.null=] <var ignore>t</var>, return null.
 1. If |w| is of the form [=ref.func=] |funcaddr|, return the result of creating [=a new Exported Function=] from |funcaddr|.
-1. If |w| is of the form [=ref.host=] |hostaddr|, return the result of [=retrieving a host value=] from |hostaddr|.
+1. If |w| is of the form [=ref.extern=] |externaddr|, return the result of [=retrieving an extern value=] from |externaddr|.
 
 <!-- If the WebAssembly value is optional, then given `None`, return JavaScript value `undefined`. -->
 
 Note: Number values which are equal to NaN may have various observable NaN payloads; see [=NumberToRawBytes=] for details.
 </div>
 
 <div algorithm>
-    For <dfn>retrieving a host value</dfn> from a [=host address=] |hostaddr|, perform the following steps:
-    1. Let |map| be the [=surrounding agent=]'s associated [=host value cache=].
-    1. Assert: |map|[|hostaddr|] [=map/exists=].
-    1. Return |map|[|hostaddr|].
+    For <dfn>retrieving an extern value</dfn> from a [=extern address=] |externaddr|, perform the following steps:
+    1. Let |map| be the [=surrounding agent=]'s associated [=extern value cache=].
+    1. Assert: |map|[|externaddr|] [=map/exists=].
+    1. Return |map|[|externaddr|].
 </div>
 
 <div algorithm>
@@ -1095,28 +1097,24 @@ The algorithm <dfn>ToWebAssemblyValue</dfn>(|v|, |type|) coerces a JavaScript va
 1. If |type| is [=f64=],
     1. Let |f64| be ? [=ToNumber=](|v|).
     1. Return [=f64.const=] |f64|.
-1. Assert: |type| is a reference type.
-1. If |type| is [=externref=],
-    1. Do nothing.
 1. If |type| is [=funcref=],
-    1. If |v| is not an [=Exported function=] or null, throw a {{TypeError}}.
-1. Return the result of [=allocating a host address=] for |v|.
-
-</div>
-
-<div algorithm>
-    For <dfn>allocating a host address</dfn> for a value |v|, perform the following steps:
     1. If |v| is null,
-        1. Return [=ref.null=].
+        1. Return [=ref.null=] [=funcref=].
     1. If |v| is an [=Exported Function=],
         1. Let |funcaddr| be the value of |v|'s \[[FunctionAddress]] internal slot.
         1. Return [=ref.func=] |funcaddr|.
-    1. Let |map| be the [=surrounding agent=]'s associated [=host value cache=].
-    1. If a [=host address=] |hostaddr| exists such that |map|[|hostaddr|] is the same as |v|,
-        1. Return [=ref.host=] |hostaddr|.
-    1. Let [=host address=] |hostaddr| be the smallest address such that |map|[|hostaddr|] [=map/exists=] is false.
-    1. [=map/Set=] |map|[|hostaddr|] to |v|.
-    1. Return [=ref.host=] |hostaddr|.
+    1. Throw a {{TypeError}}.
+1. If |type| is [=externref=],
+    1. If |v| is null,
+        1. Return [=ref.null=] [=externref=].
+    1. Let |map| be the [=surrounding agent=]'s associated [=extern value cache=].
+    1. If a [=extern address=] |externaddr| exists such that |map|[|externaddr|] is the same as |v|,
+        1. Return [=ref.extern=] |externaddr|.
+    1. Let [=extern address=] |externaddr| be the smallest address such that |map|[|externaddr|] [=map/exists=] is false.
+    1. [=map/Set=] |map|[|externaddr|] to |v|.
+    1. Return [=ref.extern=] |externaddr|.
+1. Assert: This step is not reached.
+
 </div>