If 'ignoreFilterIfFieldNotInIndex' set to 'true', global time filter is not working in Discover.

[prabhakarmanthena]

Kibana version: 6.3.0

Elasticsearch version:6.3.0

Description:
If we enable the "ignoreFilterIfFieldNotInIndex" in advanced settings. I observed the global time filter is not applied in the discover page.
In my opinion below thing is causing this issue.
in src\ui\public\courier\data_source\search_source.js

 this._filterPredicates = [
        (filter) => {
          // remove null/undefined filters
          return filter;
        },
        (filter) => {
          const disabled = _.get(filter, 'meta.disabled');
          return disabled === undefined || disabled === false;
        },
        (filter, state) => {
          if (!config.get('courier:ignoreFilterIfFieldNotInIndex')) {
            return true;
          }

          if ('meta' in filter && 'index' in state) {
            const field = state.index.fields.byName[filter.meta.key];
            if (!field) return false;
          }
          return true;
        }
      ];

filter.meta.key is undefined. and I didn't see filter.meta.key value defined in src\ui\public\timefilter\timefilter.js

 let filter;
      const timefield = indexPattern.timeFieldName && _.find(indexPattern.fields, { name: indexPattern.timeFieldName });

      if (timefield) {
        const bounds = timeRange ? this.calculateBounds(timeRange) : this.getBounds();
        filter = { range: {} };
        filter.range[timefield.name] = {
          gte: bounds.min.valueOf(),
          lte: bounds.max.valueOf(),
          format: 'epoch_millis'
        };
      } 

Or in src\ui\public\courier\data_source\_root_search_source.js.

 globalSource.filter(function (globalSource) {
    // dynamic time filter will be called in the _flatten phase of things
    const filter = timefilter.get(globalSource.get('index'));
    // Attach a meta property to it, that we check inside visualizations
    // to remove that timefilter again because we use our explicitly passed in one.
    // This should be removed as soon as we got rid of inheritance in SearchSource
    // across the boundary or visualization.
    if (filter) {
      filter.meta = { _globalTimefilter: true };
    }
    return filter;
  });

Seems need to define a filter.meta.key value in timefilter.js to fix this issue.

Steps to reproduce:

1. Go to advanced settings and set 'ignoreFilterIfFieldNotInIndex' to 'true'
2. Go to discover page try to change the time filter values

Expected behavior: Irrespective of this setting global time filter should work

Screenshots (if relevant):

cc: @timroes

[Bargs]

@timroes I think this is probably a side effect of #19221. Previously the time filter would have failed this conditional but now that it has a meta prop it will pass and subsequently fail to find a field because there is no meta.key. What's funny is, I can reproduce the issue in 6.3, but not master. Are you aware of any related changes going into master but not 6.3 that might have fixed this?

[Bargs]

For some users this is making Discover totally lock up #21398

[Bargs]

I checked our 6.4 and 6.x branches and this bug is fixed in those versions as well. I believe this is the PR that probably fixed it: #19172. The meta key was being added to the time filter object in _root_search_source, which was deleted in this PR. Since this is already fixed in 6.4+ I'm going to close this ticket.