[kernel] Offsets on loops

pkg/kernel/binary.md

 This file describes the binary format of Dart Kernel.
 
 Notation
 --------
 Bitmasks are described with the syntax:
 ```scala
     Byte flags (flag1, flag2, ..., flagN)
 ```
 where 'flag<N>' is the N-th least significant bit,
 (so flag1 is the least significant bit).
@@ skipping 772 matching lines @@
 
   // Reference to the Nth LabeledStatement in scope, with 0 being the
   // outermost enclosing labeled statement within the same FunctionNode.
   //
   // Labels are not in scope across function boundaries.
   UInt labelIndex;
 }
 
 type WhileStatement extends Statement {
   Byte tag = 67;
+  FileOffset fileOffset;
   Expression condition;
   Statement body;
 }
 
 type DoStatement extends Statement {
   Byte tag = 68;
+  FileOffset fileOffset;
   Statement body;
   Expression condition;
 }
 
 type ForStatement extends Statement {
   Byte tag = 69;
+  FileOffset fileOffset;
   List<VariableDeclaration> variables;
   Option<Expression> condition;
   List<Expression> updates;
   Statement body;
 }
 
 type ForInStatement extends Statement {
   Byte tag = 70;
-  FileOffset fileOffset; // note that this is actually the body offset
+  FileOffset fileOffset;
+  FileOffset bodyOffset;
   VariableDeclaration variable;
   Expression iterable;
   Statement body;
 }
 
 type AsyncForInStatement extends Statement {
   Byte tag = 80; // Note: tag is out of order.
-  FileOffset fileOffset; // note that this is actually the body offset
+  FileOffset fileOffset;
+  FileOffset bodyOffset;
   VariableDeclaration variable;
   Expression iterable;
   Statement body;
 }
 
 type SwitchStatement extends Statement {
   Byte tag = 71;
   Expression expression;
   List<SwitchCase> cases;
 }
@@ skipping 183 matching lines @@
   Option<DartType> bound;
 }
 
 type TypeParameter {
   // Note: there is no tag on TypeParameter
   StringReference name; // Cosmetic, may be empty, not unique.
   DartType bound; // 'dynamic' if no explicit bound was given.
 }
 
 ```