[JS] File reader attempts to load the same dictionary batch more than once

[asfimport]

If more than one field references the same dictionary, the JS impl will try to load its dictionary batch into a vector one time for each field.

Reporter: Brian Hulette / @TheNeuralBit
Assignee: Brian Hulette / @TheNeuralBit

Related issues:

• [JS] Error reading dictionary-encoded integration test files (is part of)

PRs and other links:

• GitHub Pull Request #1222

_{Note: This issue was originally created as ARROW-1698. Please see the migration documentation for further details.}

[asfimport]

Wes McKinney / @wesm:
Issue resolved by pull request 1222
#1222