Delete remaining commented out syncs.

These sync calls are truly redundant - when we are in a simple
alternative block, we can recover sufficiently with `recoverInline`, and
so the syncs do not add anything.

runtime-testsuite/resources/org/antlr/v4/test/runtime/templates/ParserErrors/Index.stg

@@ -11,6 +11,7 @@ TestTemplates ::= [
 	"LL2": [],
 	"LL3": [],
 	"LLStar": [],
+	"SingleTokenDeletionBeforeAlt": [],
 	"SingleTokenDeletionBeforePredict": [],
 	"SingleTokenDeletionBeforeLoop": [],
 	"MultiTokenDeletionBeforeLoop": [],

runtime-testsuite/resources/org/antlr/v4/test/runtime/templates/ParserErrors/SingleTokenDeletionBeforeAlt.stg

@@ -0,0 +1,28 @@
+TestType() ::= "Parser"
+
+Options ::= [
+	"Debug": false
+]
+
+Grammar ::= [
+	"T": {<grammar("T")>}
+]
+
+Input() ::= "ac"
+
+Rule() ::= "a"
+
+Output() ::= <<
+>>
+
+Errors() ::= <<
+line 1:0 extraneous input 'a' expecting {'b', 'c'}
+>>
+
+grammar(grammarName) ::= <<
+grammar <grammarName>;
+a : ('b' | 'c')
+;
+q : 'a'
+;
+>>

tool/resources/org/antlr/v4/tool/templates/codegen/Java/Java.stg

@@ -469,7 +469,6 @@ CodeBlockForAlt(currentAltCodeBlock, locals, preamble, ops) ::= <<
 
 LL1AltBlock(choice, preamble, alts, error) ::= <<
 setState(<choice.stateNumber>);
-<!_errHandler.sync(this);!>
 <if(choice.label)><labelref(choice.label)> = _input.LT(1);<endif>
 <preamble; separator="\n">
 switch (_input.LA(1)) {
@@ -483,7 +482,6 @@ default:
 
 LL1OptionalBlock(choice, alts, error) ::= <<
 setState(<choice.stateNumber>);
-<!_errHandler.sync(this);!>
 switch (_input.LA(1)) {
 <choice.altLook,alts:{look,alt| <cases(ttypes=look)>
 	<alt>
@@ -495,7 +493,6 @@ default:
 
 LL1OptionalBlockSingleAlt(choice, expr, alts, preamble, error, followExpr) ::= <<
 setState(<choice.stateNumber>);
-<!_errHandler.sync(this);!>
 <preamble; separator="\n">
 if (<expr>) {
 	<alts; separator="\n">