Hacky streaming of VariableGet

Hacky streaming of VariableGet

BUG=

[jensj, 2017-04-03 08:33:59]

jensj@google.com changed reviewers:
+ kmillikin@google.com

[Kevin Millikin (Google), 2017-04-05 08:59:57]

LGTM with better comments, and a better commit message.

https://codereview.chromium.org/2790093002/diff/1/pkg/kernel/binary.md
File pkg/kernel/binary.md (right):

https://codereview.chromium.org/2790093002/diff/1/pkg/kernel/binary.md#newcod...
pkg/kernel/binary.md:341: UInt variableDeclarationPosition; // Notice that this
field is temporary.
I don't think the comment belongs here.  But do say that it is the offset of the
declaration.

https://codereview.chromium.org/2790093002/diff/1/pkg/kernel/lib/ast.dart
File pkg/kernel/lib/ast.dart (right):

https://codereview.chromium.org/2790093002/diff/1/pkg/kernel/lib/ast.dart#new...
pkg/kernel/lib/ast.dart:3461: int tempOffset;
Name should be something like binaryOffset.

Comment should be something simple like // Offset of the declaration, set and
used when writing the binary.

https://codereview.chromium.org/2790093002/diff/1/pkg/kernel/lib/binary/ast_f...
File pkg/kernel/lib/binary/ast_from_binary.dart (right):

https://codereview.chromium.org/2790093002/diff/1/pkg/kernel/lib/binary/ast_f...
pkg/kernel/lib/binary/ast_from_binary.dart:640: readUInt(); // offset in binary.
Unused here.
// Offset of the declaration.

I think it's obvious that it's unused from the code.

https://codereview.chromium.org/2790093002/diff/1/pkg/kernel/lib/binary/ast_t...
File pkg/kernel/lib/binary/ast_to_binary.dart (right):

https://codereview.chromium.org/2790093002/diff/1/pkg/kernel/lib/binary/ast_t...
pkg/kernel/lib/binary/ast_to_binary.dart:905: int length = _sink.flushedLength +
_sink.length - (hasTag ? 1 : 0);
It seems better to move writing of the tag here so you have something like:

node.binaryPosition = ...;
if (hasTag) writeByte(Tag.VariableDeclaration);
writeOffset(node.fileOffset);
...