White space character next to emoji icons are sometimes not rendered

**Guake version**

```
➜ guake --version
Guake Terminal: 3.7.0
VTE: 0.60.3
VTE runtime: 0.60.3
Gtk: 3.24.20
```

**Describe the bug**

White space character next to emoji icons are sometimes not rendered or are rendered narrower than they should be (e.g. when on the right side of the emoji, there's a white space).

FYI, some other terminal emulators exhibit the same problem (e.g. GNOME Terminal 3.36.1.1).

**Expected behavior**

This text to be rendered with one white space on left, and one white space on the right side of the cloud emoji (font: Monospace Regular 12):

```
~/Downloads on ☁️ behrangsa
```

**Actual behavior**

The actual rendering is like this:


Compare this to how xed renders the same string using the same font:


**To Reproduce**

* Set the font to Monospace Regular 12
* Paste "~/Downloads on ☁️ behrangsa" on the terminal
* The whitespace on the right side of the cloud emoji does not seem to be rendered or it is rendered very narrowly

-------------------------------------------------------------------------------

Please run `$ guake --support`, and paste the results here. Don't put backticks (`` ` ``) around it! The output already contains Markdown formatting. And make sure you run the command **OUTSIDE** the Guake.

$ guake --support

Guake Version: 3.7.0

Vte Version: 0.60.3

Vte Runtime Version: 0.60.3

--------------------------------------------------
GTK+ Version: 3.24.20

GDK Backend: GdkX11.X11Display

--------------------------------------------------
Desktop Session: cinnamon

--------------------------------------------------
Display: :0

RGBA visual: True

Composited: True

* Monitor: 0 - DEL DisplayPort-2
* Geometry: 2560 x 1440 at 2560, 0
* Size: 597 x 336 mm²
* Primary: True
* Refresh rate: 59.95 Hz
* Subpixel layout: unknown
* Monitor: 1 - DEL DisplayPort-4
* Geometry: 2560 x 1440 at 0, 0
* Size: 597 x 336 mm²
* Primary: False
* Refresh rate: 59.95 Hz
* Subpixel layout: unknown