Go constants with omitted assignment are not syntax highlighted correctly

[segevfiner]

• VSCode Version: 1.35.1
• OS Version: macOS 10.14.5

Steps to Reproduce:

1. Open the following .go file in VS Code:

package foo

const (
	Value1 = iota
	Value2
	Value3
	Value4
)

2. Value2, Value3 and Value4 are not highlighted like Value1.

Does this issue occur when all extensions are disabled?: Yes

[alexr00]

Moved the issue to go grammar repo.

[segevfiner]

@alexr00 The issue on the Go grammer repo was punted on since they don't seem to be interested in maintaining the Go TextMate grammer as they are migrating to a different engine for syntax highlighting in Atom.