Prevent estimate if frontend provider is browser wallet

[darwintree]

The following code might fail from the sdk auto-estimation

const hash = await xxxContract.doXXX(param1).sendTransaction({from: addr})

For example, if there is not enough balance for addr, an error will happen and developer needs to handle the error themselves.

However, this situation can be prevented if developr manually encode the transaction parameters and call the cfx_sendTransaction method rather than using the sdk provided method. In that case the browser wallet could handle the error and tell the user the problem is insufficient balance.

It is suggested to improve the implementation to reduce the work dapp developers need to do.