regexp: grow slices dynamically in the 'All' routines.

R=rsc
CC=golang-dev
https://golang.org/cl/1953044
diff --git a/src/pkg/regexp/find_test.go b/src/pkg/regexp/find_test.go
index 5d1a67a..d0aad82 100644
--- a/src/pkg/regexp/find_test.go
+++ b/src/pkg/regexp/find_test.go
@@ -84,6 +84,16 @@
 		`!"#$%&'()*+,-./:;<=>?@[\]^_{|}~`, build(1, 0, 31)},
 	FindTest{"\\`", "`", build(1, 0, 1)},
 	FindTest{"[\\`]+", "`", build(1, 0, 1)},
+
+	// long set of matches (longer than startSize)
+	FindTest{
+		".",
+		"qwertyuiopasdfghjklzxcvbnm1234567890",
+		build(36, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8, 8, 9, 9, 10,
+			10, 11, 11, 12, 12, 13, 13, 14, 14, 15, 15, 16, 16, 17, 17, 18, 18, 19, 19, 20,
+			20, 21, 21, 22, 22, 23, 23, 24, 24, 25, 25, 26, 26, 27, 27, 28, 28, 29, 29, 30,
+			30, 31, 31, 32, 32, 33, 33, 34, 34, 35, 35, 36),
+	},
 }
 
 // build is a helper to construct a [][]int by extracting n sequences from x.