Try using built-in Node.js Blob

[dumbmatter]

Node.js now has a built-in Blob, so maybe I can use that rather than

fakeIndexedDB/src/test/web-platform-tests/wpt-env.js

Lines 7 to 11 in a1c1488

	global.Blob = function (parts, options = {}) {
	this.size = 0;
	Object.assign(this, options);
	return this;
	};

and maybe also enable some skipped tests that use Blobs.

[dumbmatter]

Currently the keypath-special-identifiers test fails when trying to set a value for an autoincrementing key in the "size" property, apparently that's supposed to overwrite the size of the Blob? Not sure how I should handle that.