[kernel] Offsets on loops

pkg/kernel/lib/binary/ast_to_binary.dart

Index: pkg/kernel/lib/binary/ast_to_binary.dart
diff --git a/pkg/kernel/lib/binary/ast_to_binary.dart b/pkg/kernel/lib/binary/ast_to_binary.dart
index 7b57e7bbcce4d2df1a5de82723e07bd0069da60f..f3d181eb68a1508333b49d90fba3f46025e08b4c 100644
--- a/pkg/kernel/lib/binary/ast_to_binary.dart
+++ b/pkg/kernel/lib/binary/ast_to_binary.dart
@@ -947,12 +947,14 @@ class BinaryPrinter extends Visitor {
 
   visitWhileStatement(WhileStatement node) {
     writeByte(Tag.WhileStatement);
+    writeOffset(node.fileOffset);
     writeNode(node.condition);
     writeNode(node.body);
   }
 
   visitDoStatement(DoStatement node) {
     writeByte(Tag.DoStatement);
+    writeOffset(node.fileOffset);
     writeNode(node.body);
     writeNode(node.condition);
   }
@@ -960,6 +962,7 @@ class BinaryPrinter extends Visitor {
   visitForStatement(ForStatement node) {
     _variableIndexer.pushScope();
     writeByte(Tag.ForStatement);
+    writeOffset(node.fileOffset);
     writeVariableDeclarationList(node.variables);
     writeOptionalNode(node.condition);
     writeNodeList(node.updates);
@@ -971,6 +974,7 @@ class BinaryPrinter extends Visitor {
     _variableIndexer.pushScope();
     writeByte(node.isAsync ? Tag.AsyncForInStatement : Tag.ForInStatement);
     writeOffset(node.fileOffset);
+    writeOffset(node.bodyOffset);

[ahe, 2017/08/08 11:38:50]

Notice how we don't need to document that we're writing the offset of the body.
This information is implicit in the names of the variables. Contrast this to the
comments in the flow graph builder.

     writeVariableDeclaration(node.variable);
     writeNode(node.iterable);
     writeNode(node.body);