Check if set(Body|Html)Attributes functions exist before using (#2476)

Since older versions of Gatsby won't have them.

Author: KyleAMathews

packages/gatsby-plugin-react-helmet/src/gatsby-ssr.js

@@ -5,8 +5,13 @@ exports.onRenderBody = (
   pluginOptions
 ) => {
   const helmet = Helmet.renderStatic()
-  setHtmlAttributes(helmet.htmlAttributes.toComponent())
-  setBodyAttributes(helmet.bodyAttributes.toComponent())
+  // These action functions were added partway through the Gatsby 1.x cycle.
+  if (setHtmlAttributes) {
+    setHtmlAttributes(helmet.htmlAttributes.toComponent())
+  }
+  if (setBodyAttributes) {
+    setBodyAttributes(helmet.bodyAttributes.toComponent())
+  }
   setHeadComponents([
     helmet.title.toComponent(),
     helmet.link.toComponent(),

packages/gatsby-remark-images/src/__tests__/__snapshots__/index.js.snap

@@ -6,7 +6,7 @@ exports[`it transforms HTML img tags 1`] = `
   
   <span class=\\"gatsby-resp-image-wrapper\\" style=\\"position: relative; display: block; ; max-width: 300px; margin-left: auto; margin-right: auto;\\">
     <span class=\\"gatsby-resp-image-background-image\\" style=\\"padding-bottom: 133.33333333333331%; position: relative; bottom: 0; left: 0; background-image: url(&apos;url(&apos;data:image/png;base64, iVBORw)&apos;); background-size: cover; display: block;\\">
-      <img class=\\"gatsby-resp-image-image\\" style=\\"width: 100%; margin: 0; vertical-align: middle; position: absolute; top: 0; left: 0; box-shadow: inset 0px 0px 0px 400px white;\\" alt=\\"my image\\" title=\\"\\" src=\\"not-a-real-dir/image/my-image.jpeg\\" srcset=\\"not-a-real-dir/image/my-image.jpeg, not-a-real-dir/image/my-image.jpeg\\" sizes=\\"(max-width: 650px) 100vw, 650px\\">
+      <img class=\\"gatsby-resp-image-image\\" style=\\"width: 100%; height: 100%; margin: 0; vertical-align: middle; position: absolute; top: 0; left: 0; box-shadow: inset 0px 0px 0px 400px white;\\" alt=\\"my image\\" title=\\"\\" src=\\"not-a-real-dir/image/my-image.jpeg\\" srcset=\\"not-a-real-dir/image/my-image.jpeg, not-a-real-dir/image/my-image.jpeg\\" sizes=\\"(max-width: 650px) 100vw, 650px\\">
     </span>
   </span>
   
@@ -34,7 +34,7 @@ exports[`it transforms images in markdown 1`] = `
     >
       <img
         class=\\"gatsby-resp-image-image\\"
-        style=\\"width: 100%; margin: 0; vertical-align: middle; position: absolute; top: 0; left: 0; box-shadow: inset 0px 0px 0px 400px white;\\"
+        style=\\"width: 100%; height: 100%; margin: 0; vertical-align: middle; position: absolute; top: 0; left: 0; box-shadow: inset 0px 0px 0px 400px white;\\"
         alt=\\"image\\"
         title=\\"\\"
         src=\\"not-a-real-dir/images/my-image.jpeg\\"