Reapply "Lazy deopt without code patching."

runtime/vm/stub_code_ia32.cc

Index: runtime/vm/stub_code_ia32.cc
diff --git a/runtime/vm/stub_code_ia32.cc b/runtime/vm/stub_code_ia32.cc
index fab258eea6ec7eeac9598770bacfb2ced10c340b..0473a0d5db7548fb2c22ee3146f0f5f1ff4f5ab4 100644
--- a/runtime/vm/stub_code_ia32.cc
+++ b/runtime/vm/stub_code_ia32.cc
@@ -461,27 +461,19 @@ static void GenerateDeoptimizationSequence(Assembler* assembler,
 }
 
 
-// TOS: return address + call-instruction-size (5 bytes).
 // EAX: result, must be preserved
 void StubCode::GenerateDeoptimizeLazyFromReturnStub(Assembler* assembler) {
-  // Correct return address to point just after the call that is being
-  // deoptimized.
-  __ popl(EBX);
-  __ subl(EBX, Immediate(CallPattern::pattern_length_in_bytes()));
-  __ pushl(EBX);
+  // Return address for "call" to deopt stub.
+  __ pushl(Immediate(0xe1e1e1e1));
   GenerateDeoptimizationSequence(assembler, kLazyDeoptFromReturn);
 }
 
 
-// TOS: return address + call-instruction-size (5 bytes).
 // EAX: exception, must be preserved
 // EDX: stacktrace, must be preserved
 void StubCode::GenerateDeoptimizeLazyFromThrowStub(Assembler* assembler) {
-  // Correct return address to point just after the call that is being
-  // deoptimized.
-  __ popl(EBX);
-  __ subl(EBX, Immediate(CallPattern::pattern_length_in_bytes()));
-  __ pushl(EBX);
+  // Return address for "call" to deopt stub.
+  __ pushl(Immediate(0xe1e1e1e1));
   GenerateDeoptimizationSequence(assembler, kLazyDeoptFromThrow);
 }