rename fill attribute

Summary:
We were using `fill={true}` as an attribute to make flexbox containers fill the entire available space.

However, `fill` is an HTML attribute (see: https://developer.mozilla.org/en-US/docs/Web/SVG/Attribute/fill) This caused warnings printed to the console.

This diff renames the attribute to `grow` with is also more in line with the Flexbox terminology.

Reviewed By: priteshrnandgaonkar

Differential Revision: D10488389

fbshipit-source-id: ed8553c6203cdf6df94d26c731164ecec4c9fbd2

src/plugins/sandbox/index.js

@@ -103,7 +103,7 @@ export default class SandboxView extends FlipperPlugin<SandboxState> {
     return (
       <FlexColumn>
         <SandboxView.TextInputLayout>
-          <ButtonGroup flexGrow={1}>
+          <ButtonGroup flexgrow={true}>
             <SandboxView.TextInput
               type="text"
               placeholder="Sandbox URL (e.g. unixname.sb.facebook.com)"