Split yet more runtime functions into separate files.

BUILD.gn

Index: BUILD.gn
diff --git a/BUILD.gn b/BUILD.gn
index 5ba74eb4561cff8d26d6948e613932b3c877d2e6..f7a6ba9a4fd0de3cb69c8f5fada09c4e2c6b1565 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -830,13 +830,19 @@ source_set("v8_base") {
     "src/runtime/runtime-i18n.cc",
     "src/runtime/runtime-date.cc",
     "src/runtime/runtime-debug.cc",
+    "src/runtime/runtime-function.cc",
     "src/runtime/runtime-generator.cc",
     "src/runtime/runtime-json.cc",
+    "src/runtime/runtime-literals.cc",
     "src/runtime/runtime-liveedit.cc",
     "src/runtime/runtime-maths.cc",
     "src/runtime/runtime-numbers.cc",
+    "src/runtime/runtime-observe.cc",
+    "src/runtime/runtime-proxy.cc",
     "src/runtime/runtime-regexp.cc",
+    "src/runtime/runtime-scopes.cc",
     "src/runtime/runtime-strings.cc",
+    "src/runtime/runtime-symbol.cc",
     "src/runtime/runtime-test.cc",
     "src/runtime/runtime-typedarray.cc",
     "src/runtime/runtime-uri.cc",