Add support for "else if" in gyp conditions

test/conditions/elseif/elseif.gyp

Index: test/conditions/elseif/elseif.gyp
diff --git a/test/conditions/elseif/elseif.gyp b/test/conditions/elseif/elseif.gyp
new file mode 100644
index 0000000000000000000000000000000000000000..8d0e05a6d194dd3a209fd5dde540a834737c54e7
--- /dev/null
+++ b/test/conditions/elseif/elseif.gyp
@@ -0,0 +1,31 @@
+# Copyright (c) 2014 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+{
+  'variables': {
+    'test_var%': 0,
+  },
+  'targets': [
+    {
+      'target_name': 'program',
+      'type': 'executable',
+      'sources': [
+        'program.cc',
+      ],
+      'conditions': [
+        ['test_var==0', {
+          'defines': ['FOO="first_if"'],
+        }, 'test_var==1', {

[scottmg, 2014/11/14 17:09:44]

I applaud the effort to make elseifs better, but without syntax I worry this is
making the conditions blocks even more subtle to read. (Not bad here, but when
there's longer contained blocks)

Maybe gyp-developer@ has some opinions either way.

[Shezan Baig (Bloomberg), 2014/11/14 17:25:44]

This is true.  In our code, we've been using this patch locally and formatting
the conditions like:

    ['test_var==0', {
    },
    'test_var==1', {
    },
    'test_var==2', {
    }],

IMO this makes it a bit easier to parse mentally, and it makes sense in our code
because our internal C/C++ coding style puts 'else' statements on a new line. 
But for this test, I was trying to follow how 'else' looks using the chromium
C++ coding style.

+          'defines': ['FOO="first_else_if"'],
+        }, 'test_var==2', {
+          'defines': ['FOO="second_else_if"'],
+        }, 'test_var==3', {
+          'defines': ['FOO="third_else_if"'],
+        }, {
+          'defines': ['FOO="last_else"'],
+        }],
+      ],
+    },
+  ],
+}