more visual context about the scope of variables displayed while debugging

[devoncarew]

More visual context of the scope of variables (params, locals, instance vars, top-level).

[devoncarew]

Removed this from the M4 milestone.
Added this to the M5 milestone.

[devoncarew]

Removed this from the M5 milestone.
Added this to the M6 milestone.

[devoncarew]

Removed this from the M6 milestone.
Added this to the M7 milestone.

[devoncarew]

Removed this from the M7 milestone.
Added this to the Later milestone.

[danrubel]

Removed this from the Later milestone.
Added this to the M9 milestone.

[devoncarew]

Removed this from the M9 milestone.
Added this to the Later milestone.

[devoncarew]

Fixed in https://codereview.chromium.org/158453003/.

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Added Fixed label.

[clayberg]

Removed this from the Later milestone.
Added this to the 1.2 milestone.