whitespace indicators are bold when the theme is bold

[Tyriar]

• VSCode Version: Code - Insiders 1.9.0-insider (ab491d3, 2016-12-30T07:11:50.471Z)
• OS Version: Windows_NT ia32 10.0.14986
• Extensions:

Extension	Author	Version
vscode-svgviewer	cssho	1.3.0
EditorConfig	EditorConfig	0.3.4
git-project-manager	felipecaputo	1.0.0
md-navigate	jrieken	0.0.1
vscode-scss	mrmlnc	0.6.0
seti-icons	qinjia	0.1.3
lorem-ipsum	Tyriar	1.0.0
terminal-tabs	Tyriar	0.0.6
theme-glacier	Tyriar	0.0.10