dashboard: test darwin/386 on macOS 10.14

Fixes golang/go#31719

Change-Id: I35ffac5a4e52c424f5b397f742dab6cbf1586b64
Reviewed-on: https://go-review.googlesource.com/c/build/+/174319
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
diff --git a/dashboard/builders_test.go b/dashboard/builders_test.go
index ef50d67..803464c 100644
--- a/dashboard/builders_test.go
+++ b/dashboard/builders_test.go
@@ -449,7 +449,7 @@
 		{b("darwin-amd64-10_11", "net"), none},
 		{b("darwin-amd64-10_11@go1.11", "net"), none},
 		{b("darwin-amd64-10_11@go1.12", "net"), none},
-		{b("darwin-386-10_11@go1.11", "net"), none},
+		{b("darwin-386-10_14@go1.11", "net"), none},
 
 		{b("darwin-amd64-10_14", "go"), onlyPost},
 		{b("darwin-amd64-10_12", "go"), onlyPost},
@@ -457,9 +457,9 @@
 		{b("darwin-amd64-10_10", "go"), none},
 		{b("darwin-amd64-10_10@go1.12", "go"), onlyPost},
 		{b("darwin-amd64-10_10@go1.11", "go"), onlyPost},
-		{b("darwin-386-10_11", "go"), onlyPost},
-		{b("darwin-386-10_11@go1.12", "go"), onlyPost},
-		{b("darwin-386-10_11@go1.11", "go"), onlyPost},
+		{b("darwin-386-10_14", "go"), onlyPost},
+		{b("darwin-386-10_14@go1.12", "go"), onlyPost},
+		{b("darwin-386-10_14@go1.11", "go"), onlyPost},
 
 		// plan9 only lived at master. We didn't support any past releases.
 		// But it's off for now as it's always failing.