exp/norm: generate trie struct in triegen.go for better encapsulation.

R=r, r
CC=golang-dev
https://golang.org/cl/4837071

src/pkg/exp/norm/trie_test.go

@@ -6,7 +6,7 @@ import (
 )
 
 // Test data is located in triedata_test.go, generated by maketesttables.
-var testdata = &trie{testdataLookup[:], testdataValues[:]}
+var testdata = testdataTrie
 
 // Test cases for illegal runes.
 type trietest struct {

src/pkg/exp/norm/triedata_test.go

@@ -59,3 +59,5 @@ var testdataLookup = [640]uint8{
 	// Block 0x9, offset 0x240
 	0x24f: 0x08,
 }
+
+var testdataTrie = trie{testdataLookup[:], testdataValues[:]}

src/pkg/exp/norm/triegen.go

@@ -206,5 +206,6 @@ func (t *trieNode) printTables(name string) int {
 		printLookupBlock(i, index.lookupBlocks[i], 0x80)
 	}
 	fmt.Print("\n}\n\n")
+	fmt.Printf("var %sTrie = trie{ %sLookup[:], %sValues[:] }\n\n", name, name, name)
 	return nv*2 + ni
 }