dart2js: remove trailing 0 byte when reading .packages

pkg/compiler/lib/src/apiimpl.dart

Index: pkg/compiler/lib/src/apiimpl.dart
diff --git a/pkg/compiler/lib/src/apiimpl.dart b/pkg/compiler/lib/src/apiimpl.dart
index f8695bba1a20c7753c52781d8779c343dd1e4c7a..f274c5e9482572e90897552bcb0a7652ac0a3529 100644
--- a/pkg/compiler/lib/src/apiimpl.dart
+++ b/pkg/compiler/lib/src/apiimpl.dart
@@ -392,6 +392,12 @@ class Compiler extends leg.Compiler {
         if (packageConfigContents is String) {
           packageConfigContents = UTF8.encode(packageConfigContents);
         }
+        // The input provider may put a trailing 0 byte when it reads a source

[Siggi Cherem (dart-lang), 2015/08/13 00:52:19]

I'm surprised that we get a null terminated string - any reason why the input
provider is including that?

[Harry Terkelsen, 2015/08/13 17:02:41]

I asked Johnni about it this morning. It apparently speeds up scanning to have
the trailing sentinel \0.

+        // file, which confuses the package config parser.
+        if (packageConfigContents.length > 0
+            && packageConfigContents.last == 0) {
+          packageConfigContents = packageConfigContents.removeLast();
+        }
         packages =
             new MapPackages(pkgs.parse(packageConfigContents, packageConfig));
       });