Fix step ordering in WritableStream constructor

Closes #346. Thanks @msssk!

index.bs

@@ -1364,9 +1364,9 @@ Instances of <code>WritableStream</code> are created with the internal slots des
   1. Set *this*@[[queue]] to a new empty List.
   1. Set *this*@[[state]] to "writable".
   1. Set *this*@[[started]] and *this*@[[writing]] to *false*.
-  1. Call-with-rethrow SyncWritableStreamStateWithQueue(*this*).
   1. Let _normalizedStrategy_ be ValidateAndNormalizeQueuingStrategy(_size_, _highWaterMark_).
   1. Set *this*@[[strategySize]] to _normalizedStrategy_.[[size]] and *this*@[[strategyHWM]] to _normalizedStrategy_.[[highWaterMark]].
+  1. Call-with-rethrow SyncWritableStreamStateWithQueue(*this*).
   1. Let _error_ be a new <a><code>WritableStream</code> error function</a>.
   1. Set _error_@[[stream]] to *this*.
   1. Let _startResult_ be InvokeOrNoop(_underlyingSink_, "start", «_error_»).
@@ -2928,6 +2928,7 @@ Ed Hager,
 Forbes Lindesay,
 贺师俊 (hax),
 Jens Nockert,
+Mangala Sadhu Sangeet Singh Khalsa,
 Marcos Caceres,
 Michael Mior,
 Tab Atkins,

reference-implementation/lib/writable-stream.js

@@ -26,11 +26,11 @@ export default class WritableStream {
     this._strategySize = normalizedStrategy.size;
     this._strategyHWM = normalizedStrategy.highWaterMark;
 
+    SyncWritableStreamStateWithQueue(this);
+
     const error = closure_WritableStreamErrorFunction();
     error._stream = this;
 
-    SyncWritableStreamStateWithQueue(this);
-
     const startResult = InvokeOrNoop(underlyingSink, 'start', [error]);
     this._startedPromise = Promise.resolve(startResult);
     this._startedPromise.then(() => {