gn format: penalty-based scheme for line breaking

tools/gn/format_test_data/042.gn

-# Test both one element and two element for specifically name LHSs.
+# Test zero, one, and multiple element for specifically named LHSs.
 if (true) {
+  cflags = []
+  cflags_c = []
+  cflags_cc = []
+  data = []
+  datadeps = []
+  defines = []
+  deps = []
+  include_dirs = []
+  inputs = []
+  ldflags = []
+  public_deps = []
+  sources = []
+} else if (true) {
+  cflags = [ "x" ]
+  cflags_c = [ "x" ]
+  cflags_cc = [ "x" ]
+  data = [ "x" ]
+  datadeps = [ "x" ]
+  defines = [ "x" ]
   deps = [ "x" ]
+  include_dirs = [ "x" ]
+  inputs = [ "x" ]
+  ldflags = [ "x" ]
+  public_deps = [ "x" ]
   sources = [ "x" ]
-  public_deps = [ "x" ]
-  include_dirs = ["x"]
-  defines = ["x"]
-  cflags = ["x"]
 } else {
-  deps = [ "x", "y" ]
-  sources = [ "x", "y" ]
-  public_deps = [ "x", "y" ]
-  include_dirs = ["x", "y"]
-  defines = ["x", "y"]
-  cflags = ["x", "y"]
+  cflags = [ "x", "y", "z"]
+  cflags_c = [ "x", "y", "z"]
+  cflags_cc = [ "x", "y", "z"]
+  data = [ "x", "y", "z"]
+  datadeps = [ "x", "y", "z"]
+  defines = [ "x", "y", "z"]
+  deps = [ "x", "y", "z"]
+  include_dirs = [ "x", "y", "z"]
+  inputs = [ "x", "y", "z"]
+  ldflags = [ "x", "y", "z"]
+  public_deps = [ "x", "y", "z"]
+  sources = [ "x", "y", "z"]
 }