Fix several failing tests

pkg/analyzer/lib/src/fasta/ast_builder.dart

Index: pkg/analyzer/lib/src/fasta/ast_builder.dart
diff --git a/pkg/analyzer/lib/src/fasta/ast_builder.dart b/pkg/analyzer/lib/src/fasta/ast_builder.dart
index c6f57cea7b1b7bb065b097aada8bc69c5879a607..524b1fd7e6ed900ea9440fdbf68339721a90a2d0 100644
--- a/pkg/analyzer/lib/src/fasta/ast_builder.dart
+++ b/pkg/analyzer/lib/src/fasta/ast_builder.dart
@@ -1226,9 +1226,6 @@ class AstBuilder extends ScopeListener {
   void endConditionalUri(Token ifKeyword, Token equalitySign) {
     debugEvent("ConditionalUri");
     StringLiteral libraryUri = pop();
-    // TODO(paulberry,ahe): the parser should report the right paren token to
-    // the listener.
-    Token rightParen = null;
     StringLiteral value;
     if (equalitySign != null) {
       value = pop();
@@ -1239,6 +1236,9 @@ class AstBuilder extends ScopeListener {
     // recovery and then report both the ifKeyword and leftParen tokens to the
     // listener.
     Token leftParen = ifKeyword.next;
+    // TODO(paulberry,ahe): the parser should report the right paren token to
+    // the listener.

[danrubel, 2017/08/30 17:44:03]

Is this comment still valid? Are there situations in which `rightParen` is not
')' ?

[Brian Wilkerson, 2017/08/30 18:03:49]

I think so...

If the paren is missing, or if there are tokens between the name and the paren
that are discarded during recovery, we'll get the wrong token here. This code
should probably check the token type and set `rightParen` to null to help catch
that case. But in order to get it right, the listener really needs the parser to
send it *all* of the tokens rather than having any of them inferred by location.

+    Token rightParen = name.endToken.next;
     push(ast.configuration(ifKeyword, leftParen, name, equalitySign, value,
         rightParen, libraryUri));
   }