webperf: Introduce 'templates' in test fixture and use for mwload

Authored by Krinkle on Jan 12 2018, 9:30 PM.

Description

webperf: Introduce 'templates' in test fixture and use for mwload

  • Create a 'templates' key in the fixture that the test runner ignores.
  • Move the existing 'expected_uncached_desktop' list there.
  • Abstract another template list for 'expected_uncached_desktop_mwload' that is also used by the non-navtiming test.
  • Add 'flatten()' utility method given the ref/merge ref/extend syntax only works for key-value objects (dict) in YAML, not for sequences (list).

Change-Id: Ib43ab6a2d21c3148a4ce8954cc81166ebc2c0237