unicode/bidi: remove unused global

It seems like controlToClass variable is not used anymore.
As it allocates in init we should remove it.
Before:
init golang.org/x/text/unicode/bidi @0.70 ms, 0.003 ms clock, 272 bytes, 2 allocs
After:
init golang.org/x/text/unicode/bidi @0.79 ms, 0 ms clock, 0 bytes, 0 allocs

Change-Id: I79b236feb841c45908431cdb440bd1f4eb082d00
Reviewed-on: https://go-review.googlesource.com/c/text/+/449595
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Auto-Submit: Ian Lance Taylor <iant@google.com>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Run-TryBot: Ian Lance Taylor <iant@google.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>

unicode/bidi/gen_trieval.go

diff --git a/unicode/bidi/gen_trieval.go b/unicode/bidi/gen_trieval.go
index eac0f76..d565b7c 100644
--- a/unicode/bidi/gen_trieval.go
+++ b/unicode/bidi/gen_trieval.go
@@ -42,18 +42,6 @@
 	unknownClass = ^Class(0)
 )
 
-var controlToClass = map[rune]Class{
-	0x202D: LRO, // LeftToRightOverride,
-	0x202E: RLO, // RightToLeftOverride,
-	0x202A: LRE, // LeftToRightEmbedding,
-	0x202B: RLE, // RightToLeftEmbedding,
-	0x202C: PDF, // PopDirectionalFormat,
-	0x2066: LRI, // LeftToRightIsolate,
-	0x2067: RLI, // RightToLeftIsolate,
-	0x2068: FSI, // FirstStrongIsolate,
-	0x2069: PDI, // PopDirectionalIsolate,
-}
-
 // A trie entry has the following bits:
 // 7..5  XOR mask for brackets
 // 4     1: Bracket open, 0: Bracket close

unicode/bidi/trieval.go

diff --git a/unicode/bidi/trieval.go b/unicode/bidi/trieval.go
index 4c459c4..6a796e2 100644
--- a/unicode/bidi/trieval.go
+++ b/unicode/bidi/trieval.go
@@ -37,18 +37,6 @@
 	unknownClass = ^Class(0)
 )
 
-var controlToClass = map[rune]Class{
-	0x202D: LRO, // LeftToRightOverride,
-	0x202E: RLO, // RightToLeftOverride,
-	0x202A: LRE, // LeftToRightEmbedding,
-	0x202B: RLE, // RightToLeftEmbedding,
-	0x202C: PDF, // PopDirectionalFormat,
-	0x2066: LRI, // LeftToRightIsolate,
-	0x2067: RLI, // RightToLeftIsolate,
-	0x2068: FSI, // FirstStrongIsolate,
-	0x2069: PDI, // PopDirectionalIsolate,
-}
-
 // A trie entry has the following bits:
 // 7..5  XOR mask for brackets
 // 4     1: Bracket open, 0: Bracket close