[turbofan] Implement throwing exceptions into TurboFan code.

test/cctest/compiler/test-run-jsexceptions.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/v8.h"
 
 #include "test/cctest/compiler/function-tester.h"
 
 using namespace v8::internal;
 using namespace v8::internal::compiler;
 
 TEST(Throw) {
   i::FLAG_turbo_exceptions = true;
   FunctionTester T("(function(a,b) { if (a) { throw b; } else { return b; }})");
 
   T.CheckThrows(T.true_value(), T.NewObject("new Error"));
   T.CheckCall(T.Val(23), T.false_value(), T.Val(23));
 }
 
 
 TEST(ThrowSourcePosition) {
+  i::FLAG_turbo_exceptions = true;
   static const char* src =
       "(function(a, b) {        \n"
       "  if (a == 1) throw 1;   \n"
       "  if (a == 2) {throw 2}  \n"
       "  if (a == 3) {0;throw 3}\n"
       "  throw 4;               \n"
       "})                       ";
   FunctionTester T(src);
   v8::Handle<v8::Message> message;
 
@@ skipping 95 matching lines @@
       "    r += 'A-';"
       "    return r + 'B-' + fun();"
       "  } catch (e) {"
       "    r += e;"
       "  }"
       "  return r;"
       "})";
   FunctionTester T(src);
 
   CompileRun("function thrower() { throw 'T-'; }");
-#if 0  // TODO(mstarzinger): Enable once we have exception handlers.
   T.CheckCall(T.Val("-A-T-"), T.NewFunction("thrower"));
-#endif
   CompileRun("function returner() { return 'R-'; }");
   T.CheckCall(T.Val("-A-B-R-"), T.NewFunction("returner"));
 }
 
 
 TEST(Finally) {
   i::FLAG_turbo_exceptions = true;
   const char* src =
       "(function(a,b) {"
       "  var r = '-';"
@@ skipping 102 matching lines @@
       "  } finally {"
       "    %DeoptimizeFunction(f);"
       "  }"
       "})";
   FunctionTester T(src);
 
 #if 0  // TODO(mstarzinger): Enable once we can.
   T.CheckThrows(T.NewObject("new Error"), T.Val(1));
 #endif
 }