open Istanbul and MuirGlacier from ChainConfig (#645)

* open Istanbul and MuirGlacier

* fix ut

* fix ut

x/evm/types/chain_config.go

@@ -85,8 +85,8 @@ func DefaultChainConfig() ChainConfig {
 		ByzantiumBlock:      sdk.ZeroInt(),
 		ConstantinopleBlock: sdk.ZeroInt(),
 		PetersburgBlock:     sdk.ZeroInt(),
-		IstanbulBlock:       sdk.NewInt(-1),
-		MuirGlacierBlock:    sdk.NewInt(-1),
+		IstanbulBlock:       sdk.ZeroInt(),
+		MuirGlacierBlock:    sdk.ZeroInt(),
 		YoloV2Block:         sdk.NewInt(-1),
 		EWASMBlock:          sdk.NewInt(-1),
 	}

x/evm/types/chain_config_test.go

@@ -236,8 +236,8 @@ eip158_block: "0"
 byzantium_block: "0"
 constantinople_block: "0"
 petersburg_block: "0"
-istanbul_block: "-1"
-muir_glacier_block: "-1"
+istanbul_block: "0"
+muir_glacier_block: "0"
 yoloV2_block: "-1"
 ewasm_block: "-1"
 `