use api to getTokenInfo.

[todo]

aelf-web-wallet/app/web/js/utils/crossChain.js

Lines 71 to 76 in 55ce713

	// TODO: use api to getTokenInfo.
	// A good news is that we only support AELF, EPC, EDA, EDB, EDC, EDD to crossChain now.
	mainChainId: this.WEB_API_INFO.AELF.id,
	issueChainId,
	queryLimit: 1
	});

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This issue was generated by todo based on a TODO comment in 55ce713 when #56 was merged. cc @AElfProject.