fix macro with injected renderBody migration

[mlrawlings]

Description

In addition to <macro-body> a special renderBody property used to be injected into the <macro> tag. The migration did not account for this.

<macro test()>
  $ renderBody(out);
</macro>

Checklist:

• I have read the CONTRIBUTING document and have signed (or will sign) the CLA.
• I have updated/added documentation affected by my changes.
• I have added tests to cover my changes.

[codecov]

Codecov Report

Merging #1300 into master will increase coverage by 0.02%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master    #1300      +/-   ##
==========================================
+ Coverage   90.54%   90.56%   +0.02%     
==========================================
  Files         339      339              
  Lines       12411    12416       +5     
==========================================
+ Hits        11237    11245       +8     
+ Misses       1174     1171       -3

Impacted Files	Coverage Δ
src/taglibs/migrate/macro-tag.js	100% <100%> (ø)	⬆️
src/compiler/Walker.js	93.75% <0%> (+3.75%)	⬆️

---

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 d161213...cc2a4c9. Read the comment docs.

[coveralls]

Coverage increased (+0.03%) to 90.569% when pulling cc2a4c9 on macro-renderbody-fix into d161213 on master.