Replace single quotes with double quotes to fix BUILD.gn

TBR=jochen@chromium.org

Review URL: https://codereview.chromium.org/665313003

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@24785 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

BUILD.gn

@@ -583,8 +583,8 @@ source_set("v8_base") {
     "src/compiler/value-numbering-reducer.h",
     "src/compiler/verifier.cc",
     "src/compiler/verifier.h",
-    'src/compiler/zone-pool.cc',
-    'src/compiler/zone-pool.h',
+    "src/compiler/zone-pool.cc",
+    "src/compiler/zone-pool.h",
     "src/compiler.cc",
     "src/compiler.h",
     "src/contexts.cc",