Roll DEPS for PDFium: Switch from master branch to xfa branch.
Roll DEPS for PDFium: Switch from master branch to xfa branch.

XFA features are still disabled.

BUG=62400

Review URL: https://codereview.chromium.org/1577853003

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#368779}

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