Rename ContainerNode method recalcChildStyle to recalcDescendantStyles

To make the name more accurate. This rename change was also mentioned
in the Design Doc for splitting up Style Resolution and Layout Tree
Construction here:
https://drive.google.com/open?id=1RlEfhfUnhIEJSgV0nb8AKT4uyWbNsSY_k9uSGTUCQ2I

BUG=595137

Review-Url: https://codereview.chromium.org/1899643002
Cr-Commit-Position: refs/heads/master@{#408004}
4 files changed