Ignore all environment variables with name starting with '='

sdk/lib/io/platform_impl.dart

Index: sdk/lib/io/platform_impl.dart
diff --git a/sdk/lib/io/platform_impl.dart b/sdk/lib/io/platform_impl.dart
index 0cffec6a532bd98f77549122771e11297bec48ff..e0d485bf3d47b70591daa6ccb8f8bec1496ec2d0 100644
--- a/sdk/lib/io/platform_impl.dart
+++ b/sdk/lib/io/platform_impl.dart
@@ -62,14 +62,14 @@ class _Platform {
           // environment variables that are used to record the current
           // working directory for each drive and the exit code for the
           // last command. As an example: '=A:=A:\subdir' records the
-          // current working directory on the 'A' drive.  In order to
-          // handle these correctly we search for a second occurrence of
-          // of '=' in the string if the first occurrence is at index 0.
+          // current working directory on the 'A' drive. These environment
+          // variables are ignored.
+          //
+          // On Mac OS an entry of just '=' has been seen.

[Lasse Reichstein Nielsen, 2015/01/05 11:45:43]

Add: Entries with no '=' should not happen. If it should happen, the entry is
ignored.

[Søren Gjesse, 2015/01/05 12:32:14]

Done.

           var equalsIndex = str.indexOf('=');
-          if (equalsIndex == 0) {
-            equalsIndex = str.indexOf('=', 1);
+          if (equalsIndex == 0 || equalsIndex == -1) {

[Lasse Reichstein Nielsen, 2015/01/05 11:45:43]

equalsIndex <= 0
?

But switch the condition and avoid the continue:

if (equalsIndex > 0) {
  result[...] = ...;
}

[Søren Gjesse, 2015/01/05 12:32:14]

Done.

+            continue;
           }
-          assert(equalsIndex != -1);
           result[str.substring(0, equalsIndex)] =
               str.substring(equalsIndex + 1);
         }