Revert "JS: remove else in second/third/... else-if when preceded by …

…a return/break/continue/throw statement", fixes #509

This reverts commit a665158.

js/js_test.go

@@ -255,7 +255,6 @@ func TestJS(t *testing.T) {
 		{`if(a){}else{while(b);}`, `if(a);else for(;b;);`},
 		{`if(a){return b}else{while(c);}`, `if(a)return b;for(;c;);`},
 		{`if(a){return b}else{while(c);d}`, `if(a)return b;for(;c;);d`},
-		{`if(a)b;else if(c)return d;else if(e)return f`, `if(a)b;else if(c)return d;if(e)return f`},
 		{`if(!a){while(b);c}`, `if(!a){for(;b;);c}`},
 		{`while(a){if(b)continue;if(c)continue;else d}`, `for(;a;){if(b)continue;if(c)continue;d}`},
 		{`while(a)if(b)continue;else c`, `for(;a;){if(b)continue;c}`},

js/stmtlist.go

@@ -146,7 +146,6 @@ func optimizeStmtList(list []js.IStmt, blockType blockType) []js.IStmt {
 	for i := 0; i < len(list); i++ { // read index
 		if ifStmt, ok := list[i].(*js.IfStmt); ok && !isEmptyStmt(ifStmt.Else) {
 			// if(!a)b;else c  =>  if(a)c; else b
-		IfElseLoop:
 			if unary, ok := ifStmt.Cond.(*js.UnaryExpr); ok && unary.Op == js.NotToken && isFlowStmt(lastStmt(ifStmt.Else)) {
 				ifStmt.Cond = unary.X
 				ifStmt.Body, ifStmt.Else = ifStmt.Else, ifStmt.Body
@@ -160,8 +159,6 @@ func optimizeStmtList(list []js.IStmt, blockType blockType) []js.IStmt {
 					list = append(list[:i+1], append([]js.IStmt{ifStmt.Else}, list[i+1:]...)...)
 				}
 				ifStmt.Else = nil
-			} else if ifStmt, ok = ifStmt.Else.(*js.IfStmt); ok && !isEmptyStmt(ifStmt.Else) {
-				goto IfElseLoop
 			}
 		}