lib: fix sequence argument handling in Blob constructor

This uses the existing WebIDL infrastructure to handle the iteration
over the argument correctly according to the specification.

Note that we can't avoid looping over the input twice: we only know the
value of the 'endings' option after converting the blob parts into an array.

Author: Ms2ger

lib/internal/blob.js

@@ -1,7 +1,6 @@
 'use strict';
 
 const {
-  ArrayFrom,
   MathMax,
   MathMin,
   ObjectDefineProperties,
@@ -15,7 +14,6 @@ const {
   StringPrototypeSplit,
   StringPrototypeToLowerCase,
   Symbol,
-  SymbolIterator,
   SymbolToStringTag,
   Uint8Array,
 } = primordials;
@@ -54,12 +52,15 @@ const {
   lazyDOMException,
 } = require('internal/util');
 const { inspect } = require('internal/util/inspect');
-const { convertToInt } = require('internal/webidl');
+const {
+  converters,
+  convertToInt,
+  createSequenceConverter,
+} = require('internal/webidl');
 
 const {
   codes: {
     ERR_BUFFER_TOO_LARGE,
-    ERR_INVALID_ARG_TYPE,
     ERR_INVALID_ARG_VALUE,
     ERR_INVALID_STATE,
     ERR_INVALID_THIS,
@@ -112,7 +113,6 @@ function getSource(source, endings) {
   if (isAnyArrayBuffer(source)) {
     source = new Uint8Array(source);
   } else if (!isArrayBufferView(source)) {
-    source = `${source}`;
     if (endings === 'native')
       source = RegExpPrototypeSymbolReplace(/\n|\r\n/g, source, EOL);
     source = enc.encode(source);
@@ -126,6 +126,13 @@ function getSource(source, endings) {
   return [byteLength, new Uint8Array(slice)];
 }
 
+const sourcesConverter = createSequenceConverter((source, opts = kEmptyObject) => {
+  if (isBlob(source) || isAnyArrayBuffer(source) || isArrayBufferView(source)) {
+    return source;
+  }
+  return converters.DOMString(source, opts);
+});
+
 class Blob {
   /**
    * @typedef {string|ArrayBuffer|ArrayBufferView|Blob} SourcePart
@@ -142,11 +149,8 @@ class Blob {
   constructor(sources = [], options) {
     markTransferMode(this, true, false);
 
-    if (sources === null ||
-        typeof sources[SymbolIterator] !== 'function' ||
-        typeof sources === 'string') {
-      throw new ERR_INVALID_ARG_TYPE('sources', 'a sequence', sources);
-    }
+    const sources_ = sourcesConverter(sources);
+
     validateDictionary(options, 'options');
     let {
       endings = 'transparent',
@@ -158,11 +162,11 @@ class Blob {
       throw new ERR_INVALID_ARG_VALUE('options.endings', endings);
 
     let length = 0;
-    const sources_ = ArrayFrom(sources, (source) => {
-      const { 0: len, 1: src } = getSource(source, endings);
+    for (let i = 0; i < sources_.length; ++i) {
+      const { 0: len, 1: src } = getSource(sources_[i], endings);
       length += len;
-      return src;
-    });
+      sources_[i] = src;
+    }
 
     if (length > kMaxLength)
       throw new ERR_BUFFER_TOO_LARGE(kMaxLength);

test/wpt/status/FileAPI/blob.json

@@ -4,14 +4,6 @@
   },
   "Blob-constructor.any.js": {
     "fail": {
-      "expected": [
-        "blobParts not an object: boolean with Boolean.prototype[Symbol.iterator]",
-        "blobParts not an object: number with Number.prototype[Symbol.iterator]",
-        "blobParts not an object: BigInt with BigInt.prototype[Symbol.iterator]",
-        "blobParts not an object: Symbol with Symbol.prototype[Symbol.iterator]",
-        "Getters and value conversions should happen in order until an exception is thrown.",
-        "Arguments should be evaluated from left to right."
-      ],
       "flaky": [
         "Passing typed arrays as elements of the blobParts array should work.",
         "Passing a Float16Array as element of the blobParts array should work.",