Clean up temporary variable usage in ScalarizeVecAndMatConstructorArgs Use common helper functions instead of manually creating temporary variable nodes. Also clean up the interface provided by the traverser. BUG=angleproject:1597 Test=WebGL conformance tests Change-Id: Ifd8d3815ff9e75e1a2040d65db9d4b3d6a9a9273 Reviewed-on: https://chromium-review.googlesource.com/403950 Reviewed-by: Corentin Wallez <cwallez@chromium.org> Reviewed-by: Jamie Madill <jmadill@chromium.org> Commit-Queue: Olli Etuaho <oetuaho@nvidia.com>