Update the org.realityforge.com.google.elemental2 dependency.

Author: realityforge

CHANGELOG.md

@@ -2,6 +2,8 @@
 
 ### Unreleased
 
+* Upgrade the `org.realityforge.com.google.elemental2` artifacts to version `1.0.0-b21-6a027d2`.
+
 ### [v1.66](https://github.com/react4j/react4j-windowportal/tree/v1.66) (2019-04-07)
 [Full Changelog](https://github.com/react4j/react4j-windowportal/compare/v1.65...v1.66)
 

build.yaml

@@ -19,9 +19,9 @@ artifacts:
 
   jsinterop_base: org.realityforge.com.google.jsinterop:base:jar:1.0.0-b2-e6d791f
 
-  elemental2_core: org.realityforge.com.google.elemental2:elemental2-core:jar:1.0.0-b20-bfe6e22
-  elemental2_dom: org.realityforge.com.google.elemental2:elemental2-dom:jar:1.0.0-b20-bfe6e22
-  elemental2_promise: org.realityforge.com.google.elemental2:elemental2-promise:jar:1.0.0-b20-bfe6e22
+  elemental2_core: org.realityforge.com.google.elemental2:elemental2-core:jar:1.0.0-b21-6a027d2
+  elemental2_dom: org.realityforge.com.google.elemental2:elemental2-dom:jar:1.0.0-b21-6a027d2
+  elemental2_promise: org.realityforge.com.google.elemental2:elemental2-promise:jar:1.0.0-b21-6a027d2
 
   react4j_core: org.realityforge.react4j:react4j-core:jar:0.124
   react4j_dom: org.realityforge.react4j:react4j-dom:jar:0.124