Fix nativeClient available checks

Author: HazAT

lib/Sentry.js

@@ -58,7 +58,10 @@ export class Sentry {
   }
 
   static isNativeClientAvailable() {
-    return Sentry._nativeClient !== undefined;
+    return (
+      Sentry._nativeClient !== undefined &&
+      Sentry.options.disableNativeIntegration === false
+    );
   }
 
   static _log(...args) {

lib/raven-plugin.js

@@ -75,7 +75,7 @@ function reactNativePlugin(Raven, options, internalDataCallback) {
     })
   );
 
-  if (options.nativeClientAvailable && options.nativeClientAvailable === false) {
+  if (options.nativeClientAvailable === false) {
     // react-native doesn't have a document, so can't use default Image
     // transport - use XMLHttpRequest instead
     Raven.setTransport(reactNativePlugin._transport);