Turn off ASAN for non-default toolchains for win clang.

build/toolchain/win/BUILD.gn

Index: build/toolchain/win/BUILD.gn
diff --git a/build/toolchain/win/BUILD.gn b/build/toolchain/win/BUILD.gn
index 5e61c02082c2f8a4df40c8400c1aa1b65d57ca17..815bdffc1f31e4bb16d3a0f8c8423bf6e251f4bf 100644
--- a/build/toolchain/win/BUILD.gn
+++ b/build/toolchain/win/BUILD.gn
@@ -268,6 +268,9 @@ template("msvc_toolchain") {
       if (defined(invoker.is_component_build)) {
         is_component_build = invoker.is_component_build
       }
+      if (defined(invoker.is_asan)) {
+        is_asan = invoker.is_asan
+      }
 
       # This value needs to be passed through unchanged.
       host_toolchain = host_toolchain
@@ -352,6 +355,9 @@ template("win_x64_toolchains") {
     if (defined(invoker.is_component_build)) {
       is_component_build = invoker.is_component_build
     }
+    if (defined(invoker.is_asan)) {
+      is_asan = invoker.is_asan
+    }
   }
 
   msvc_toolchain("clang_" + target_name) {
@@ -368,6 +374,9 @@ template("win_x64_toolchains") {
     if (defined(invoker.is_component_build)) {
       is_component_build = invoker.is_component_build
     }
+    if (defined(invoker.is_asan)) {
+      is_asan = invoker.is_asan
+    }
   }
 }
 
@@ -377,6 +386,9 @@ win_x64_toolchains("x64") {
   concurrent_links = concurrent_links
   goma_prefix = goma_prefix
   x64_toolchain_data = x64_toolchain_data
+  if (target_cpu == "x86") {
+    is_asan = false
+  }
 }
 
 # The nacl_win64 toolchain is nearly identical to the plain x64 toolchain.
@@ -386,6 +398,7 @@ win_x64_toolchains("x64") {
 # building nacl64.exe in component style does not work.
 win_x64_toolchains("nacl_win64") {
   is_component_build = false
+  is_asan = false
 
   # TODO(mcgrathr): These assignments are only required because of
   # crbug.com/395883.  Drop them if that ever gets fixed in GN.