"Close Editor" in the File menu did not get the correct translation value

[noneghost]

Bug Description:

"Close Editor" in the File menu did not get the correct translation value after use mater branch.

Steps to Reproduce:

After #13331

theia/packages/editor/src/browser/editor-menu.ts

Lines 180 to 184 in b15b639

	registry.registerMenuAction(CommonMenus.FILE_CLOSE, {
	commandId: CommonCommands.CLOSE_MAIN_TAB.id,
	label: nls.localizeByDefault('Close Editor'),
	order: '1'
	});

1. Get "Close Editor" value when use "Close Editor" key, Get right value when use "close Editor" key.
2. It may be due to a mismatch in the DefaultKey values obtained by nls.

theia/packages/core/src/common/nls.ts

Lines 90 to 94 in b15b639

	get(defaultValue: string): string | undefined {
	const normalized = Localization.normalize(defaultValue);
	return this.data.get(normalized) || this.data.get(normalized.toUpperCase());
	}

Additional Information

• Theia Version: master branch (commit id: b15b639)