Inconsistent Sizing on \overleftarrow

Created by: matoushs

\overleftarrow appears smaller than \overrightarrow

Issue Summary

The over left arrow is considerably smaller than the over right arrow with HTML-CSS renderer. This TeX code: $\overrightarrow{R} \overleftarrow{R} \leftarrow \rightarrow$, renders as:

The MML code shows stretchy=false on the left arrow:

<math xmlns="http://www.w3.org/1998/Math/MathML">
  <mover>
    <mi>R</mi>
    <mo>&#x2192;<!-- → --></mo>
  </mover>
  <mover>
    <mi>R</mi>
    <mo>&#x2190;<!-- ← --></mo>
  </mover>
  <mo stretchy="false">&#x2190;<!-- ← -->&#x2192;<!-- → --></mo>
</math>

After reading #1470 (closed) I added the STIX font to my configuration file:

"HTML-CSS": { preferredFont: "STIX" }

The font is STIX, but the arrows are still different.

Technical details:

• MathJax Version: 2.3 (latest commit: f3aaf3a2)
• Client OS: Mac OS X 10.14.3
• Browser: Firefox Developer - Aurora