fix: bad assertion in crypto functions that use BN_bn2bin_padded (#17220)

* chore: roll node

in particular, this picks up electron/node#70a78f07b, which fixes an issue with incorrect usage of the BN_bn2bin_padded API in boringssl

* fix tests

DEPS

@@ -12,7 +12,7 @@ vars = {
   'chromium_version':
     '73.0.3683.65',
   'node_version':
-    'fac6d766c143db8db05bb3b0c0871df8f032363c',
+    '70a78f07b1c4d53f3da462b08cef42a4ff8f949f',
 
   'boto_version': 'f7574aa6cc2c819430c1f05e9a1a1a666ef8169b',
   'pyyaml_version': '3.12',

spec/node-spec.js

@@ -472,6 +472,21 @@ describe('node feature', () => {
       const iv = Buffer.from('fedcba9876543210', 'hex')
       require('crypto').createCipheriv('des-ede-cbc', key, iv)
     })
+
+    it('should not crash when getting an ECDH key', () => {
+      const ecdh = require('crypto').createECDH('prime256v1')
+      expect(ecdh.generateKeys()).to.be.an.instanceof(Buffer)
+      expect(ecdh.getPrivateKey()).to.be.an.instanceof(Buffer)
+    })
+
+    it('should not crash when generating DH keys or fetching DH fields', () => {
+      const dh = require('crypto').createDiffieHellman('modp15')
+      expect(dh.generateKeys()).to.be.an.instanceof(Buffer)
+      expect(dh.getPublicKey()).to.be.an.instanceof(Buffer)
+      expect(dh.getPrivateKey()).to.be.an.instanceof(Buffer)
+      expect(dh.getPrime()).to.be.an.instanceof(Buffer)
+      expect(dh.getGenerator()).to.be.an.instanceof(Buffer)
+    })
   })
 
   it('includes the electron version in process.versions', () => {