Refactor LoopHandler to avoid calling KernelAstAdapter.getNode

pkg/compiler/lib/src/ssa/builder.dart

Index: pkg/compiler/lib/src/ssa/builder.dart
diff --git a/pkg/compiler/lib/src/ssa/builder.dart b/pkg/compiler/lib/src/ssa/builder.dart
index 57aabba6381bd44df6869b672aa2e354317cf68a..911e2459b500d1fb66b415a76ccf6e5736b5eadd 100644
--- a/pkg/compiler/lib/src/ssa/builder.dart
+++ b/pkg/compiler/lib/src/ssa/builder.dart
@@ -1744,7 +1744,8 @@ class SsaBuilder extends ast.Visitor
   visitDoWhile(ast.DoWhile node) {
     assert(isReachable);
     LocalsHandler savedLocals = new LocalsHandler.from(localsHandler);
-    localsHandler.startLoop(node);
+    ClosureScope scopeData = localsHandler.closureData.capturingScopes[node];
+    localsHandler.startLoop(scopeData);

[Emily Fortuna, 2017/06/09 20:12:26]

great minds think alike?

I actually have a CL that does this same thing (passing in the data instead of
the node) that I was working on yesterday evening, but didn't send out yet for
review: https://codereview.chromium.org/2932103002 

So... maybe hold off on this part? I didn't do the change about making the
localsMap non-private though, so that could go in. I should have this other CL
ready for review by EOD today, so you can take a look -- it's in a similar but
slightly different direction than this one, so I welcome your input.

[Johnni Winther, 2017/06/12 08:02:52]

I'll wait for your CL to land

     loopDepth++;
     JumpHandler jumpHandler = loopHandler.beginLoopHeader(node);
     HLoopInformation loopInfo = current.loopInformation;
@@ -1762,7 +1763,7 @@ class SsaBuilder extends ast.Visitor
       // Using a separate block is just a simple workaround.
       bodyEntryBlock = openNewBlock();
     }
-    localsHandler.enterLoopBody(node);
+    localsHandler.enterLoopBody(scopeData);
     visit(node.body);
 
     // If there are no continues we could avoid the creation of the condition