[Bug] SVG text border does not work in Safari

[hughess]

Version

5.4.2

Link to Minimal Reproduction

https://echarts.apache.org/examples/en/editor.html?c=line-smooth&version=5.4.2&renderer=svg&code=PYBwLglsB2AEC8sDeAoWsAeBBDEDOAXMmurGAJ4gCmRA5AMYCGYVA5sAE7m0A0J6AE2aMiAbVoBZGL1i0AKgFcqM2gHUqAlXIAWClQDEOEFQGVmphdFoBdEgF8-6cjnxFUpMpRqyAbowA2Srz8sNCMALbeAETksIy4eKERVFF8AJBpYZFyVBhgJhT-3qgZGSx5AEKcAlQcAMLA_px0AO7aECzBpWnlYFUcNRyqEAJg2kQATOmlAGYw-RAAXt4TAAwopQ72jrB4tRBUhLCiIe4esEJgIscAHGs8sACcAMxTT6sAjA8vACwPHxNHqt_s9nsDYB9XqtrDsPBRqHR_BBoMpYaQ8OFgMAxkQwBwlCE7CQYSQwFj_JAQG4QniIKxWLU6PF8LR7Cg7ABuIA

Steps to Reproduce

1. Add a text border to any text on your chart (example link shows y-axis name)
2. Open chart in Safari
3. Engage the tooltip on the chart by hovering over a point
4. The text which has the text border will flicker and change so that the entirety of the text is the colour of the text border

Current Behavior

In Safari, text with a text border will flicker when the chart is interacted with. This is most apparent when you interact with a tooltip, but also happens when hovering over the axes of the chart.

Expected Behavior

Text should not flicker.

Environment

- OS: Mac OS Monterey
- Browser: Safari Version 15.1 (17612.2.9.1.20)
- Framework: N/A

Any additional comments?

I added a text border to an element I am adding to our charting library and found that it does not work in mobile Safari or in desktop Safari. I will have to hold off on adding this feature until it's supported across all browsers.