Revert "Refactor constant part."

dart/frog/leg/ssa/codegen.dart

Index: dart/frog/leg/ssa/codegen.dart
diff --git a/dart/frog/leg/ssa/codegen.dart b/dart/frog/leg/ssa/codegen.dart
index 8dcea37326116f6160ad793be17c0b27d6d061c4..80d3b6d3654504a44836b1147322b7590b3a8d7c 100644
--- a/dart/frog/leg/ssa/codegen.dart
+++ b/dart/frog/leg/ssa/codegen.dart
@@ -654,19 +654,35 @@ class SsaCodeGenerator implements HVisitor {
     endExpression(JSPrecedence.MEMBER_PRECEDENCE);
   }
 
-  visitConstant(HConstant node) {
-    // TODO(floitsch): the compile-time constant handler and the codegen
-    // need to work together to avoid the parenthesis. See r4928 for an
-    // implementation that still dealt with precedence.
-    ConstantHandler handler = compiler.constantHandler;
-    String name = handler.getNameForConstant(node.constant);
-    if (name === null) {
-      assert(!node.constant.isObject());
-      node.constant.writeJsCode(buffer, handler);
+  visitLiteral(HLiteral node) {
+    if (node.isLiteralNull()) {
+      beginExpression(JSPrecedence.PREFIX_PRECEDENCE);
+      buffer.add("void 0");
+      endExpression(JSPrecedence.PREFIX_PRECEDENCE);
+    } else if (node.value is num) {
+      int precedence = JSPrecedence.PRIMARY_PRECEDENCE;
+      if (node.value < 0 ||
+          expectedPrecedence == JSPrecedence.MEMBER_PRECEDENCE) {
+        // Negative constants are really unary minus operator expressions.
+        // If the constant appear as a MemberExpression, it might be subject
+        // to the '.' operator, which shouldn't be put next to a number
+        // literal. It might be mistaken for a decimal point. Setting
+        // precedence to PREFIX_PRECEDENCE forces parentheses in this case.
+        precedence = JSPrecedence.PREFIX_PRECEDENCE;
+      }
+      beginExpression(precedence);
+      buffer.add(node.value);
+      endExpression(precedence);
+    } else if (node.isLiteralString()) {
+      DartString string = node.value;
+      buffer.add("'");
+      CompileTimeConstantHandler.writeEscapedString(string, buffer,
+                                                    (String reason) {
+        compiler.cancel(reason, instruction: node);
+      });
+      buffer.add("'");
     } else {
-      buffer.add(compiler.namer.CURRENT_ISOLATE);
-      buffer.add(".");
-      buffer.add(name);      
+      buffer.add(node.value);
     }
   }
 
@@ -707,7 +723,7 @@ class SsaCodeGenerator implements HVisitor {
   visitReturn(HReturn node) {
     assert(node.inputs.length == 1);
     HInstruction input = node.inputs[0];
-    if (input.isConstantNull()) {
+    if (input.isLiteralNull()) {
       buffer.add('return;\n');
     } else {
       buffer.add('return ');