src/vs/workbench/services/keybinding/common/keybindingEditing.ts/KeybindingsEditingService/findUserKeybindingEntryIndex
class KeybindingsEditingService:	private findUserKeybindingEntryIndex(keybindingItem: ResolvedKeybindingItem, userKeybindingEntries: IUserFriendlyKeybinding[]): number {
		for (let index = 0; index < userKeybindingEntries.length; index++) {
			const keybinding = userKeybindingEntries[index];
			if (keybinding.command === keybindingItem.command) {
				if (!keybinding.when && !keybindingItem.when) {
					return index;
				}
				if (keybinding.when && keybindingItem.when) {
					const contextKeyExpr = ContextKeyExpr.deserialize(keybinding.when);
					if (contextKeyExpr && contextKeyExpr.serialize() === keybindingItem.when.serialize()) {
						return index;
					}
				}
			}
		}
		return -1;
	}