remove reference to styled components css prop (#35296)

types/rebass__grid/index.d.ts

@@ -10,7 +10,6 @@
 // TypeScript Version: 2.9
 
 import * as React from "react";
-import { Interpolation } from "styled-components";
 import * as StyledSystem from "styled-system";
 
 export {};
@@ -19,7 +18,6 @@ type Omit<T, K> = Pick<T, Exclude<keyof T, K>>;
 
 export interface BaseProps extends React.Props<any> {
     as?: React.ElementType;
-    css?: Interpolation<any>;
 }
 
 interface BoxKnownProps

types/rebass__grid/rebass__grid-tests.tsx

@@ -1,6 +1,5 @@
 import * as React from "react";
 import { Flex, Box } from "@rebass/grid";
-import { css } from "styled-components";
 import * as Emotion from "@rebass/grid/emotion";
 
 const test = () => (
@@ -118,28 +117,8 @@ const Layout = () => (
     </Flex>
 );
 
-const cssTest = (
-    <Flex css="background: transparent;">
-        <Box
-            css={css`
-                ${{ color: "inherit" }}
-            `}
-        />
-    </Flex>
-);
-
 const EmotionLayout = () => (
     <Emotion.Flex m={4}>
         <Emotion.Box px={3} py={2} />
     </Emotion.Flex>
 );
-
-const emotionCssTest = (
-    <Emotion.Flex css="background: transparent;">
-        <Emotion.Box
-            css={css`
-                ${{ color: "inherit" }}
-            `}
-        />
-    </Emotion.Flex>
-);