fix(AEX-2): Fix firefox compatibility issue

[nduchak]

No description provided.

[nduchak]

Resolve #882

[codecov]

Codecov Report

Merging #882 into develop will increase coverage by 12.96%.
The diff coverage is n/a.

@@             Coverage Diff              @@
##           develop     #882       +/-   ##
============================================
+ Coverage    79.65%   92.62%   +12.96%     
============================================
  Files           57       57               
  Lines         2846     2846               
============================================
+ Hits          2267     2636      +369     
+ Misses         579      210      -369

Impacted Files	Coverage Δ
es/utils/json-big.js	81.25% <0%> (+0.48%)	⬆️
es/contract/compiler.js	100% <0%> (+2.12%)	⬆️
es/utils/crypto.js	82.05% <0%> (+5.12%)	⬆️
es/tx/tx.js	100% <0%> (+14.45%)	⬆️
es/channel/internal.js	95.31% <0%> (+77.34%)	⬆️
es/channel/handlers.js	80.18% <0%> (+78.37%)	⬆️
es/channel/index.js	88.42% <0%> (+80%)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 0f53991...58cf874. Read the comment docs.