[cfe] Move Builder creation to helper methods

This simplifies the massive switch over fragments by moving each case implementation to its own helper method.

Change-Id: I38df8ed6106c5160eb3a033cd17f831be99de339
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/418101
Commit-Queue: Johnni Winther <johnniwinther@google.com>
Reviewed-by: Jens Johansen <jensj@google.com>

https://dart.googlesource.com/sdk/+/04faae00d5853a48ac32091f5d6d28d5f19cec07

DEPS

diff --git a/DEPS b/DEPS
index 809d59a..053da67 100644
--- a/DEPS
+++ b/DEPS
@@ -238,7 +238,7 @@
 ]
 
 deps = {
-  'flutter/engine/src/flutter/third_party/dart': Var('dart_git') + '/sdk' + '@' + '6526b26ddbadb684767182e9225a1af6b715715d',
+  'flutter/engine/src/flutter/third_party/dart': Var('dart_git') + '/sdk' + '@' + '04faae00d5853a48ac32091f5d6d28d5f19cec07',
 
   'flutter': Var('flutter_git') + '/mirrors/flutter' + '@' + '4d24ba4df2498b0d7a6d8e546955ee6c6e291a5d',
 

commits.json

diff --git a/commits.json b/commits.json
index 05c642b..907a891 100644
--- a/commits.json
+++ b/commits.json
@@ -1,4 +1,4 @@
 {
   "flutter":"4d24ba4df2498b0d7a6d8e546955ee6c6e291a5d",
-  "flutter/engine/src/flutter/third_party/dart":"6526b26ddbadb684767182e9225a1af6b715715d"
+  "flutter/engine/src/flutter/third_party/dart":"04faae00d5853a48ac32091f5d6d28d5f19cec07"
 }
\ No newline at end of file