Make react layer respect js fmt on save

The react layer relies on the javascript layer and uses multiple values
from it including definition of a formatter. However, the react layer
does not respect the javascript layer setting for formatting a file on
save.

This patch configures the react layer to add a before save hook that
calls the javascript layer formatting function when the
'javascript-fmt-on-save variable is enabled.

CHANGELOG.develop

@@ -2441,6 +2441,8 @@ Other:
   - Configure =emmet-mode= to expand classes using =className= instead of =class=
     (thanks to Sylvain Benner)
   - Open =.jsx= files with =rjsx-mode= (thanks to Thomas de Beauchêne)
+  - Made =react= layer respect =javascript= layers variable
+    =javascript-fmt-on-save= (thanks to Tommy Groshong)
 - Key bindings:
   - Added =import-js= support with key bindings:
     - ~SPC m i i~ to mport the module for the variable under the cursor

layers/+frameworks/react/funcs.el

@@ -81,3 +81,7 @@ If optional argument P is present, test this instead of point."
 
 (defun spacemacs//react-setup-yasnippet ()
   (yas-activate-extra-mode 'js-mode))
+
+;; Format
+(defun spacemacs/react-fmt-before-save-hook ()
+  (add-hook 'before-save-hook 'spacemacs/javascript-format t t))

layers/+frameworks/react/packages.el

@@ -72,6 +72,9 @@
     (add-hook 'rjsx-mode-local-vars-hook #'spacemacs//react-setup-backend)
     ;; set next-error-function to nil because we use flycheck
     (add-hook 'rjsx-mode-local-vars-hook #'spacemacs//react-setup-next-error-fn)
+    ;; setup fmt on save
+    (when javascript-fmt-on-save
+      (add-hook 'rjsx-mode-local-vars-hook 'spacemacs/react-fmt-before-save-hook))
 
     :config
     ;; declare prefix