Revise graph resource validation (#622)

* Bug fix: Make "validate graph resources" test reflexive

compute() calls validate graph resources with the passed input/output
maps and the graph's input/output descriptors. The intent is to ensure
that all of a graph's descriptors are matched to a passed resource.
However, the steps were only validating that a passed resource had a
corresponding descriptor - it wouldn't flag if a resource was missing!

The Chromium prototype implementation makes the test reflexive - all
descriptors must have a corresponding resource and all resources must
have a corresponding descriptor. Incorporate that into the spec in the
same way - if number of keys is the same, and each resource has a
descriptor, then _ipso facto_* each descriptor has a resource.

Fixes #602

(* = a Latin phrase meaning "the writer is pretentious")

* Update per discussion in PR review

* inputs must be provided, but extra inputs are ignored
* requested outputs must exist, but not all outputs must be requested

---------

Co-authored-by: Dwayne Robinson <dwayner@microsoft.com>

Author: inexorabletash

index.bs

@@ -843,16 +843,6 @@ When the {{MLContext/[[contextType]]}} is set to [=context type/default=] with t
     :: An object where the keys are the graph output names, and the values are the transferred {{ArrayBufferView}}s for the computed output tensor values.
 </dl>
 
-<details open algorithm>
-  <summary>
-    To <dfn>validate graph resources</dfn>, given {{MLNamedArrayBufferViews}} |resources| and [=ordered map=] |descriptors|, run the following steps:
-  </summary>
-    1. [=map/For each=] |name| → |resource| of |resources|:
-        1. If |descriptors|[|name|] does not [=map/exist=], return false.
-        1. If [=validating buffer with descriptor=] given |resource| and |descriptors|[|name|] returns false, then return false.
-    1. Return true.
-</details>
-
 <details open algorithm>
   <summary>
     To <dfn>validate buffer with descriptor</dfn> given {{ArrayBufferView}} |bufferView| and {{MLOperandDescriptor}} |descriptor|, run the following steps:
@@ -916,6 +906,8 @@ In accordance with the [=ArrayBufferView/write|Web IDL warning=], to prevent the
     **Returns:** Promise<{{MLComputeResult}}>.
 </div>
 
+Note: Invocations of {{MLContext/compute()}} will fail if any of the {{MLContext/compute(graph, inputs, outputs)/graph}}'s inputs are not provided as {{MLContext/compute(graph, inputs, outputs)/inputs}}, or if any requested {{MLContext/compute(graph, inputs, outputs)/outputs}} do not match the {{MLContext/compute(graph, inputs, outputs)/graph}}'s outputs.
+
 <details open algorithm>
   <summary>
     The <dfn method for=MLContext>compute(|graph|, |inputs|, |outputs|)</dfn> method steps are:
@@ -924,8 +916,12 @@ In accordance with the [=ArrayBufferView/write|Web IDL warning=], to prevent the
     1. Let |realm| be [=this=]'s [=relevant realm=].
     1. If |graph|.{{MLGraph/[[context]]}} is not [=this=], then return [=a new promise=] [=rejected=] with a {{TypeError}}.
     1. If |graph|.{{MLGraph/[[context]]}}.{{MLContext/[[contextType]]}} is not "[=context type/default=]", then return [=a new promise=] [=rejected=] with an "{{OperationError}}" {{DOMException}}.
-    1. If [=validating graph resources=] given |inputs| and |graph|.{{MLGraph/[[inputDescriptors]]}} returns false, then return [=a new promise=] [=rejected=] with a {{TypeError}}.
-    1. If [=validating graph resources=] given |outputs| and |graph|.{{MLGraph/[[outputDescriptors]]}} returns false, then return [=a new promise=] [=rejected=] with a {{TypeError}}.
+    1. [=map/For each=] |name| → |descriptor| of |graph|.{{MLGraph/[[inputDescriptors]]}}:
+        1. If |inputs|[|name|] does not [=map/exist=], then return [=a new promise=] [=rejected=] with a {{TypeError}}.
+        1. If [=validating buffer with descriptor=] given |inputs|[|name|] and |descriptor| returns false, then return [=a new promise=] [=rejected=] with a {{TypeError}}.
+    1. [=map/For each=] |name| → |resource| of |outputs|:
+        1. If |graph|.{{MLGraph/[[outputDescriptors]]}}[|name|] does not [=map/exist=], then return [=a new promise=] [=rejected=] with a {{TypeError}}.
+        1. If [=validating buffer with descriptor=] given |resource| and |graph|.{{MLGraph/[[outputDescriptors]]}}[|name|] returns false, then return [=a new promise=] [=rejected=] with a {{TypeError}}.
     1. Let |transferredInputs| be the result of [=MLNamedArrayBufferViews/transfer|transferring=] {{MLNamedArrayBufferViews}} |inputs| with |realm|. If that threw an exception, then return [=a new promise=] [=rejected=] with that exception.
     1. Let |transferredOutputs| be the result of [=MLNamedArrayBufferViews/transfer|transferring=] {{MLNamedArrayBufferViews}} |outputs| with |realm|. If that threw an exception, then return [=a new promise=] [=rejected=] with that exception.
     1. Let |promise| be [=a new promise=].