In theory, a user could define the Symbol.isConcatSpreadable property
somewhere in the TypedArray class hierarchy. Array.prototype.concat
optimizes for this case and has templated code for fast concat over
TypedArrays. However, the default environment doesn't have this
property set (it would probably not be web-compatible) and there isn't
clear demand for this optimization. This patch removes that
special-case code.

R=adamk

Review URL: https://codereview.chromium.org/1720533003

Cr-Commit-Position: refs/heads/master@{#34195}