Merge pull request #2357 from CortexFoundation/dev

remove the legacy backtraceAt method

Author: ucwong

internal/web3ext/web3ext.go

@@ -281,11 +281,6 @@ web3._extend({
 			call: 'debug_vmodule',
 			params: 1
 		}),
-		new web3._extend.Method({
-			name: 'backtraceAt',
-			call: 'debug_backtraceAt',
-			params: 1,
-		}),
 		new web3._extend.Method({
 			name: 'stacks',
 			call: 'debug_stacks',