Revert "[build] disable C++ optimization for mksnapshot code."

This reverts commit cee2f772.

Reason for revert: Breaks sanitizer builds: https://ci.chromium.org/p/v8/builders/luci.v8.ci/V8%20Linux64%20UBSan/4682

Original change's description:
> [build] disable C++ optimization for mksnapshot code.
> 
> By disabling C++ optimizations for code that's only run in mksnapshot,
> that is, CSA and Torque-generated code, we can save compile time.
> I observed up to 2x improvements of compile time for some files,
> while the mksnapshot time did not increase significantly.
> 
> Bug: v8:7629
> Change-Id: I96be2966611b2471b68023e0dd9e351d94f0013c
> Reviewed-on: https://chromium-review.googlesource.com/c/1460941
> Reviewed-by: Yang Guo <yangguo@chromium.org>
> Reviewed-by: Sigurd Schneider <sigurds@chromium.org>
> Commit-Queue: Tobias Tebbi <tebbi@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#59585}

TBR=yangguo@chromium.org,sigurds@chromium.org,tebbi@chromium.org

Change-Id: I50da40da167f49a14e3a8994377c4f9dafdfe2ab
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: v8:7629
Reviewed-on: https://chromium-review.googlesource.com/c/1472630Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
Commit-Queue: Tobias Tebbi <tebbi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#59586}

BUILD.gn

@@ -670,29 +670,6 @@ config("toolchain") {
   }
 }
 
-config("default_optimization") {
-  if (is_debug && !v8_optimized_debug) {
-    configs = [ "//build/config/compiler:no_optimize" ]
-  } else {
-    # TODO(crbug.com/621335) Rework this so that we don't have the confusion
-    # between "optimize_speed" and "optimize_max".
-    if (((is_posix && !is_android) || is_fuchsia) && !using_sanitizer) {
-      configs = [ "//build/config/compiler:optimize_speed" ]
-    } else {
-      configs = [ "//build/config/compiler:optimize_max" ]
-    }
-  }
-}
-
-# For code that is only run a few times during the build, C++ optimizations
-# are a waste of time.
-config("unoptimized_initializer") {
-  configs = [
-    ":internal_config",
-    "//build/config/compiler:no_optimize",
-  ]
-}
-
 # Configs for code coverage with gcov. Separate configs for cflags and ldflags
 # to selectively influde cflags in non-test targets only.
 config("v8_gcov_coverage_cflags") {
@@ -1007,8 +984,7 @@ v8_source_set("torque_generated_initializers") {
     ]
   }
 
-  remove_configs = [ v8_path_prefix + ":default_optimization" ]
-  configs = [ ":unoptimized_initializer" ]
+  configs = [ ":internal_config" ]
 }
 
 action("generate_bytecode_builtins_list") {
@@ -1484,8 +1460,7 @@ v8_source_set("v8_initializers") {
     sources -= [ "src/builtins/builtins-intl-gen.cc" ]
   }
 
-  remove_configs = [ v8_path_prefix + ":default_optimization" ]
-  configs = [ ":unoptimized_initializer" ]
+  configs = [ ":internal_config" ]
 }
 
 v8_source_set("v8_init") {

gni/v8.gni

@@ -94,8 +94,20 @@ v8_add_configs = [
   v8_path_prefix + ":toolchain",
 ]
 
-v8_remove_configs += [ "//build/config/compiler:default_optimization" ]
-v8_add_configs += [ v8_path_prefix + ":default_optimization" ]
+if (is_debug && !v8_optimized_debug) {
+  v8_remove_configs += [ "//build/config/compiler:default_optimization" ]
+  v8_add_configs += [ "//build/config/compiler:no_optimize" ]
+} else {
+  v8_remove_configs += [ "//build/config/compiler:default_optimization" ]
+
+  # TODO(crbug.com/621335) Rework this so that we don't have the confusion
+  # between "optimize_speed" and "optimize_max".
+  if (((is_posix && !is_android) || is_fuchsia) && !using_sanitizer) {
+    v8_add_configs += [ "//build/config/compiler:optimize_speed" ]
+  } else {
+    v8_add_configs += [ "//build/config/compiler:optimize_max" ]
+  }
+}
 
 if (v8_code_coverage && !is_clang) {
   v8_add_configs += [
@@ -137,21 +149,21 @@ template("v8_source_set") {
                              "configs",
                              "remove_configs",
                            ])
-    configs -= v8_remove_configs
-    configs += v8_add_configs
     if (defined(invoker.remove_configs)) {
       configs -= invoker.remove_configs
     }
     configs += invoker.configs
+    configs -= v8_remove_configs
+    configs += v8_add_configs
   }
 }
 
 template("v8_header_set") {
   jumbo_source_set(target_name) {
     forward_variables_from(invoker, "*", [ "configs" ])
+    configs += invoker.configs
     configs -= v8_remove_configs
     configs += v8_add_configs
-    configs += invoker.configs
   }
 }
 
@@ -163,12 +175,12 @@ template("v8_executable") {
                              "configs",
                              "remove_configs",
                            ])
-    configs -= v8_remove_configs
-    configs += v8_add_configs
     if (defined(invoker.remove_configs)) {
       configs -= invoker.remove_configs
     }
     configs += invoker.configs
+    configs -= v8_remove_configs
+    configs += v8_add_configs
     if (is_linux) {
       # For enabling ASLR.
       ldflags = [ "-pie" ]
@@ -191,9 +203,9 @@ template("v8_executable") {
 template("v8_component") {
   component(target_name) {
     forward_variables_from(invoker, "*", [ "configs" ])
+    configs += invoker.configs
     configs -= v8_remove_configs
     configs += v8_add_configs
-    configs += invoker.configs
   }
 }
 
@@ -201,9 +213,9 @@ template("v8_static_library") {
   static_library(target_name) {
     complete_static_lib = true
     forward_variables_from(invoker, "*", [ "configs" ])
+    configs += invoker.configs
     configs -= v8_remove_configs
     configs -= [ "//build/config/compiler:thin_archive" ]
     configs += v8_add_configs
-    configs += invoker.configs
   }
 }