Better screen reader support

Hello,

Some time ago I started to develop flutter applications. Unfortunately I am a visually impaired user and I cannot use the devtools because it is not screen-reader compatible.

I often find myself putting a breakpoint and performing an hot reload to see variables and widget state in the debugger, as the devtools are not accessible to screen readers.

该 issue 没有指定任何文件、测试或入口点。首先审查 DevTools 界面与屏幕阅读器的兼容性，并确定涉及的 debugger 和 hot-reload 视图。完成标准是受影响的 DevTools 工作流可通过屏幕阅读器使用，并且有测试或记录在案的验证覆盖这些更改。

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