Add "enable-aggressive-domstorage-flushing" to "WebView2 browser flags" (#3425)

* Add 'enable-aggressive-domstorage-flushing' to webview-features-flags.md

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Co-authored-by: Michael S. Hoffman <[email protected]>

Author: tamartol

Diff for: microsoft-edge/webview2/concepts/webview-features-flags.md

@@ -105,6 +105,7 @@ If the flag takes a value other than true|false, give an example. -->
 | `edge-webview-run-with-package-id` | Runs WebView processes with a package identity (package ID) for a bridged Desktop app. |
 | `edge-webview-run-without-package-id` | Runs WebView processes without a package identity (package ID) for a bridged Desktop app. |
 | `embedded-browser-webview-dpi-awareness` | Sets the DPI awareness level of the server-side processes. |
+| `enable-aggressive-domstorage-flushing` | Enables aggressive flushing of DOM Storage, to minimize data loss. |
 | `enable-experimental-web-platform-features` | Enables Web Platform features that are in development. |
 | `enable-logging` | Enable logging at the error level. |
 | `force-color-profile` | Force all monitors to be treated as though they have the specified color profile.  Valid values: `srgb`, `generic-rgb`. |