During resolution, record the target of break/continue statements.

This adds a new "target" field to BreakStatement and ContinueStatement
which points to the AST for the statement that the break/continue is
breaking from or continuing to.  For labeled break and continue
statements, this will always be the statement identified by the label
(not the LabeledStatement itself but its child).  For unlabeled break
and continue statements, this will be the innermost enclosing loop (or
switch statement, for break statements), provided that it is not in an
enclosing function.

R=brianwilkerson@google.com

Review URL: https://codereview.chromium.org//725473005

git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge@41961 260f80e4-7a28-3924-810f-c04153c831b5
Fix parsing of awaitable expressions with nested functions

“have seen await” flag must be properly saved and restored when
parsing nested function (literals) inside an await expression.

Fixes issue 21536

R=srdjan@google.com

Review URL: https://codereview.chromium.org//755053002

git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge@41962 260f80e4-7a28-3924-810f-c04153c831b5