test: fix test-buffer-slow

[targos]

Checklist

• make -j8 test (UNIX), or vcbuild test nosign (Windows) passes
• commit message follows commit guidelines

Affected core subsystem(s)

test, buffer

Description of change

Fix incorrect use of string instead of RegExp in throws assertions.

[targos]

CI: https://ci.nodejs.org/job/node-test-pull-request/4995/

[targos]

Fixed. New CI: https://ci.nodejs.org/job/node-test-pull-request/4996/

[mhdawson]

LGTM

[targos]

Landed in efcbf61

[MylesBorins]

@targos the test cherry-picks to v6.x but with a failing test

=== release test-buffer-slow ===
Path: parallel/test-buffer-slow
assert.js:355
    throw actual;
    ^

RangeError: Invalid typed array length
    at Buffer.Uint8Array (native)
    at FastBuffer (buffer.js:11:5)
    at createUnsafeBuffer (buffer.js:38:12)
    at SlowBuffer (buffer.js:159:10)
    at /Users/thealphanerd/code/node/v6.x/test/parallel/test-buffer-slow.js:53:3
    at _tryBlock (assert.js:314:5)
    at _throws (assert.js:333:12)
    at Function.assert.throws (assert.js:363:3)
    at Object.<anonymous> (/Users/thealphanerd/code/node/v6.x/test/parallel/test-buffer-slow.js:52:8)
    at Module._compile (module.js:570:32)
Command: out/Release/node /Users/thealphanerd/code/node/v6.x/test/parallel/test-buffer-slow.js

v4.x will require a manual backport

[addaleax]

I would suggest not backporting it then, the underlying cause of the different error messages has been fixed in #10152 (which has been labelled semver-major).

If somebody does want to backport this manually to v6.x or v4.x, I think they will want to do something like #9924.

/cc @joyeecheung just fyi

[joyeecheung]

I think it's better not backport this too.

[targos]

We can "backport" it by just passing the RangeError error constructor instead of a string