exp/locale/collate: from the regression test we derive that the spec

dictates a CJK rune is only part of a certain specified range if it
is explicitly defined in the Unicode Codepoint Database.
Fixed the code and some of the tests accordingly.

R=r
CC=golang-dev
https://golang.org/cl/6160044

src/pkg/exp/locale/collate/build/builder_test.go

@@ -63,7 +63,7 @@ type convertTest struct {
 
 var convLargeTests = []convertTest{
 	{pCE(0xFB39), pCE(0xFB39), false},
-	{cjk(0x2F9B2), pqCE(0x7F4F2, 0x2F9B2), false},
+	{cjk(0x2F9B2), pqCE(0x4F4F2, 0x2F9B2), false},
 	{pCE(0xFB40), pCE(0), true},
 	{append(pCE(0xFB40), pCE(0)[0]), pCE(0), true},
 	{pCE(0xFFFE), pCE(illegalOffset), false},

src/pkg/exp/locale/collate/build/colelem.go

@@ -162,16 +162,16 @@ const (
 // http://unicode.org/reports/tr10/#Implicit_Weights,
 // but preserve the resulting relative ordering of the runes.
 func implicitPrimary(r rune) int {
-	if r >= minUnified && r <= maxUnified {
-		// The most common case for CJK.
-		return int(r) + commonUnifiedOffset
-	}
-	if r >= minCompatibility && r <= maxCompatibility {
-		// This will never hit as long as we don't remove the characters
-		// that would match from the table.
-		return int(r) + commonUnifiedOffset
-	}
-	if unicode.Is(unicode.Unified_Ideograph, r) {
+	if unicode.Is(unicode.Ideographic, r) {
+		if r >= minUnified && r <= maxUnified {
+			// The most common case for CJK.
+			return int(r) + commonUnifiedOffset
+		}
+		if r >= minCompatibility && r <= maxCompatibility {
+			// This will typically not hit. The DUCET explicitly specifies mappings
+			// for all characters that do not decompose.
+			return int(r) + commonUnifiedOffset
+		}
 		return int(r) + rareUnifiedOffset
 	}
 	return int(r) + otherOffset

src/pkg/exp/locale/collate/colelem.go

@@ -154,17 +154,16 @@ const (
 // http://unicode.org/reports/tr10/#Implicit_Weights,
 // but preserve the resulting relative ordering of the runes.
 func implicitPrimary(r rune) int {
-
-	if r >= minUnified && r <= maxUnified {
-		// The most common case for CJK.
-		return int(r) + commonUnifiedOffset
-	}
-	if r >= minCompatibility && r <= maxCompatibility {
-		// This will never hit as long as we don't remove the characters
-		// that would match from the table.
-		return int(r) + commonUnifiedOffset
-	}
-	if unicode.Is(unicode.Unified_Ideograph, r) {
+	if unicode.Is(unicode.Ideographic, r) {
+		if r >= minUnified && r <= maxUnified {
+			// The most common case for CJK.
+			return int(r) + commonUnifiedOffset
+		}
+		if r >= minCompatibility && r <= maxCompatibility {
+			// This will typically not hit. The DUCET explicitly specifies mappings
+			// for all characters that do not decompose.
+			return int(r) + commonUnifiedOffset
+		}
 		return int(r) + rareUnifiedOffset
 	}
 	return int(r) + otherOffset

src/pkg/exp/locale/collate/colelem_test.go

@@ -141,7 +141,7 @@ var implicitTests = []implicitTest{
 	{0xF8FF, 0x5F43F},
 	{0xF900, 0x1F440},
 	{0xFA23, 0x1F563},
-	{0xFAFF, 0x1F63F},
+	{0xFAD9, 0x1F619},
 	{0xFB00, 0x5F640},
 	{0x20000, 0x3FB40},
 	{0x2B81C, 0x4B35C},