Fixed double onClick event on parent element

Fixes react-dropzone#252

src/index.js

@@ -17,6 +17,7 @@ class Dropzone extends React.Component {
     this.onDragOver = this.onDragOver.bind(this);
     this.onDrop = this.onDrop.bind(this);
     this.onFileDialogCancel = this.onFileDialogCancel.bind(this);
+    this.onInputClick = this.onInputClick.bind(this);
     this.fileAccepted = this.fileAccepted.bind(this);
     this.isFileDialogActive = false;
     this.state = {
@@ -144,6 +145,10 @@ class Dropzone extends React.Component {
       this.open();
     }
   }
+
+  onInputClick(e) {
+    e.stopPropagation();
+  }
 
   onFileDialogCancel() {
     // timeout will not recognize context of this method
@@ -291,6 +296,7 @@ class Dropzone extends React.Component {
         <input
           {...inputProps/* expand user provided inputProps first so inputAttributes override them */}
           {...inputAttributes}
+          onClick={this.onInputClick}
         />
       </div>
     );