Investigate missing CSS blink features

For example: https://chromestatus.com/metrics/css/timeline/popularity/516

The pages HAR dataset does include a _blinkFeatureFirstUsed.CSSFeatures property, but these are named using TitleCase convention (CSSPropertyFont), while the CSS features on Chrome Status are hyphenated (font-display). There is no feature in the HA dataset resembling “CSSFontDisplay”. These are all of the Blink features (JS, HTML, or CSS) known to HA that include “font”:

• CSSAtRuleFontFace
• kFontShapingNotDefGlyphObserved
• DocumentFonts
• FontFaceConstructor
• CSSAtRuleFontFeatureValues
• V8CSSFontFaceRule_Style_AttributeGetter
• FontSizeWebkitXxxLarge
• FontShapingNotDefGlyphObserved

It seems that HA and WPT aren’t reporting the same list of CSS features used by Chrome Status. We should figure out how to extract these feature detections from Chrome using WPT and add them to the Chrome Status dashboard.

cc @pmeenan @igrigorik

[pmeenan]

Crawl just finished so I just landed the change for next month. Truncated sample:

"_blinkFeatureFirstUsed": {
    "AnimatedCSSFeatures": [],
    "CSSFeatures": {
        "212": {
            "firstUsed": 1909.394,
            "name": "CSSPropertyAliasWebkitBoxShadow"
        },
        "130": {
            "firstUsed": 520.46299999999997,
            "name": "CSSPropertyTextIndent"
        },
        "90": {
            "firstUsed": 531.17499999999995,
            "name": "CSSPropertyMarginBottom"
        },
        "24": {
            "firstUsed": 519.58600000000001,
            "name": "CSSPropertyBackgroundColor"
        },
    },
    "Features": {
        "2712": {
            "firstUsed": 1295.3440000000001,
            "name": "WindowScreenX"
        },
        "217": {
            "firstUsed": 654.08699999999999,
            "name": "ElementPrefixedMatchesSelector"
        },
        "2710": {
            "firstUsed": 1278.7080000000001,
            "name": "WindowPageXOffset"
        },
        "2711": {
            "firstUsed": 750.44399999999996,
            "name": "WindowPageYOffset"
        }
    }
}

Yeah, I should probably round and truncate those numbers 😄, but otherwise it is done.

[rviscomi]

With @jrobbins’ help the fix is live!