Reduce the size of initial JSON string buffer.
Reduce the size of initial JSON string buffer.

BUG=v8:3925
LOG=NO

Review URL: https://codereview.chromium.org/1123013002

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#28225}

UniversalFuture/moosh,UniversalFuture/moosh,UniversalFuture/moosh,UniversalFuture/moosh