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'
-    this.query.gasPrice((err, gasPrice) => {
-      if (err) return cb(err)
-      // set gasPrice
-      txParams.gasPrice = gasPrice
-      // set gasLimit
-      this.txProviderUtils.analyzeGasUsage(txMeta, cb)
-    })
+    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 () {