WritableStream: minor bug fixes

third_party/WebKit/Source/core/streams/WritableStream.js

Index: third_party/WebKit/Source/core/streams/WritableStream.js
diff --git a/third_party/WebKit/Source/core/streams/WritableStream.js b/third_party/WebKit/Source/core/streams/WritableStream.js
index 5ffadd7e1d8967e09f4b723b892f7f2fd4b10993..7e132d97be788115a0ecd41e2de2afa710357c77 100644
--- a/third_party/WebKit/Source/core/streams/WritableStream.js
+++ b/third_party/WebKit/Source/core/streams/WritableStream.js
@@ -499,7 +499,7 @@
       if (!IsWritableStream(stream)) {
         throw new TypeError(errIllegalConstructor);
       }
-      if (stream[_controlledWritableStream] !== undefined) {
+      if (stream[_writableStreamController] !== undefined) {
         throw new TypeError(errIllegalConstructor);
       }
       this[_controlledWritableStream] = stream;
@@ -791,10 +791,7 @@
     }
 
     highWaterMark = Number(highWaterMark);
-    if (Number_isNaN(highWaterMark)) {
-      throw new TypeError(errInvalidHWM);
-    }
-    if (highWaterMark < 0) {
+    if (Number_isNaN(highWaterMark) || highWaterMark < 0) {
       throw new RangeError(errInvalidHWM);
     }