[builtins] Introduce proper Float64Tan operator.

BUILD.gn

Index: BUILD.gn
diff --git a/BUILD.gn b/BUILD.gn
index 03e05310eba24cdea847817908d5be91a4b365b6..5e248f47154c93805b675a282b6c3cd40c312c98 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -1425,8 +1425,6 @@ v8_source_set("v8_base") {
     "src/string-stream.h",
     "src/strtod.cc",
     "src/strtod.h",
-    "src/third_party/fdlibm/fdlibm.cc",
-    "src/third_party/fdlibm/fdlibm.h",
     "src/tracing/trace-event.cc",
     "src/tracing/trace-event.h",
     "src/transitions-inl.h",
@@ -2023,9 +2021,7 @@ if (current_toolchain == v8_snapshot_toolchain) {
       "src/snapshot/mksnapshot.cc",
     ]
 
-    configs = [
-      ":internal_config",
-    ]
+    configs = [ ":internal_config" ]
 
     deps = [
       ":v8_base",
@@ -2081,9 +2077,7 @@ if (is_component_build) {
       ":v8_maybe_snapshot",
     ]
 
-    configs = [
-      ":internal_config",
-    ]
+    configs = [ ":internal_config" ]
 
     public_configs = [ ":external_config" ]
   }