remove dropped handler

app/scripts/metamask-controller.js

@@ -165,7 +165,7 @@ module.exports = class MetamaskController extends EventEmitter {
     this.txController.on('newUnapprovedTx', opts.showUnapprovedTx.bind(opts))
 
     this.txController.on(`tx:status-update`, (txId, status) => {
-      if (status === 'confirmed' || status === 'failed' || status === 'dropped') {
+      if (status === 'confirmed' || status === 'failed') {
         const txMeta = this.txController.txStateManager.getTx(txId)
         this.platform.showTransactionNotification(txMeta)
       }

app/scripts/platforms/extension.js

@@ -40,8 +40,6 @@ class ExtensionPlatform {
       this._showConfirmedTransaction(txMeta)
     } else if (status === 'failed') {
       this._showFailedTransaction(txMeta)
-    } else if (status === 'dropped') {
-      this._showDroppedTransaction(txMeta)
     }
   }
 
@@ -65,14 +63,6 @@ class ExtensionPlatform {
     this._showNotification(title, message)
   }
 
-  _showDroppedTransaction (txMeta) {
-
-    const nonce = parseInt(txMeta.txParams.nonce, 16)
-    const title = 'Dropped transaction'
-    const message = `Transaction ${nonce} was dropped, because another transaction with that number was successfully processed.`
-    this._showNotification(title, message)
-  }
-
   _showNotification (title, message, url) {
     extension.notifications.create(
       url,