assert: remove unnecessary use of __proto__
assert: remove unnecessary use of __proto__

AssertionError already inherits from Error above using util.inherits(),
so this extra line was redundant.

test/simple/test-assert.js already tests for `instanceof`, and still passes.

dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node