Keeps dapp gas price if set

app/scripts/controllers/transactions.js

@@ -152,13 +152,15 @@ module.exports = class TransactionController extends EventEmitter {
     const txParams = txMeta.txParams
     // ensure value
     txParams.value = txParams.value || '0x0'
+    if (!txParams.gasPrice) {
       this.query.gasPrice((err, gasPrice) => {
         if (err) return cb(err)
         // set gasPrice
         txParams.gasPrice = gasPrice
+      })
+    }
     // set gasLimit
     this.txProviderUtils.analyzeGasUsage(txMeta, cb)
-    })
   }
 
   getUnapprovedTxList () {